To add Signature field to word template

Hi,

I have a word template in which Signature is a field.  I am capturing all the fields of this template in an Appian form.  I am capturing signature using signature field, I am using the XML functionality to populate the fields in the word template.  I am able to populate all the fields, but how can I populate the signature which is stored as a document in Appian.  Can you please help me?

Thanks