One Radio Select

I am still not clear about the problem. Can you try pasting the code snippet here?

 /*Checkbox*/
                                        a!richTextDisplayField(
                                          value: a!richTextItem(
                                            text: {
                                              a!richTextIcon(
                                                icon: "circle-o",
                                                link: a!dynamicLink(
                                                  saveInto: {
                                                    a!save(fv!item.notificacion, 1),
                                                    a!save(
                                                      ri!contactos,
                                                      rule!ERYM_ValidarNotificacionContacto(
                                                        listaContactos: ri!contactos,
                                                        idContacto: fv!item.idContacto
                                                      )
                                                    )
                                                  },
                                                  
                                                  
                                                ),
                                                linkStyle: "STANDALONE",
                                                showWhen: or(
                                                  fv!item.notificacion = 0,
                                                  isnull(fv!item.notificacion)
                                                )
                                              ),
                                              a!richTextIcon(
                                                icon: "dot-circle-o",
                                                link: a!dynamicLink(
                                                  saveInto: {
                                                    a!save(fv!item.notificacion, 0),
                                                  }
                                                ),
                                                linkStyle: "STANDALONE",
                                                showWhen: fv!item.notificacion = 1
                                              )
                                            },
                                            size: "MEDIUM"
                                          ),
                                          
                                        ),
                                        
                                        
                                        
/*Expresion Rule*/
a!forEach(
  items: ri!listaContactos,
  expression: if(
    fv!item.idContacto <> ri!idContacto,
    a!update(ri!listaContactos.notificacion, fv!item.idContacto, 1),
    ""
  )
)

 /*Checkbox*/
                                        a!richTextDisplayField(
                                          value: a!richTextItem(
                                            text: {
                                              a!richTextIcon(
                                                icon: "circle-o",
                                                link: a!dynamicLink(
                                                  saveInto: {
                                                    a!save(fv!item.notificacion, 1),
                                                    a!save(
                                                      ri!contactos,
                                                      rule!ERYM_ValidarNotificacionContacto(
                                                        listaContactos: ri!contactos,
                                                        idContacto: fv!item.idContacto
                                                      )
                                                    )
                                                  },
                                                  
                                                  
                                                ),
                                                linkStyle: "STANDALONE",
                                                showWhen: or(
                                                  fv!item.notificacion = 0,
                                                  isnull(fv!item.notificacion)
                                                )
                                              ),
                                              a!richTextIcon(
                                                icon: "dot-circle-o",
                                                link: a!dynamicLink(
                                                  saveInto: {
                                                    a!save(fv!item.notificacion, 0),
                                                  }
                                                ),
                                                linkStyle: "STANDALONE",
                                                showWhen: fv!item.notificacion = 1
                                              )
                                            },
                                            size: "MEDIUM"
                                          ),
                                          
                                        ),
                                        
                                        
                                        
/*Expresion Rule*/
a!forEach(
  items: ri!listaContactos,
  expression: if(
    fv!item.idContacto <> ri!idContacto,
    a!update(ri!listaContactos.notificacion, fv!item.idContacto, 1),
    ""
  )
)

If you are trying to select only a single row then this code differs from the solution Mike gave in the above thread shared by you, change the showWhen condition accordingly.