Table function

For me, it is pretty much unclear what you want to achieve. Can you give us a few more details?

I think you want to use your table into Appian to either fetch the data or update the data. If yes, then you have to create the CDT by using create from existing Table or view option into Data type and post that you have to provide the datastore name and the table name and after that create a constant to use that CDT into queryEntity or writetoDatastoreEntity function to fetch or update the data respectively. 

If you want to obtain data from a Table-valued Function in your database, you can create a view that queries the function, and set a data type / data store up on the view, same way as you would for a normal table. 

I do this in one scenario where a report is generated by a function that creates/returns a temporary table, ended up being better for performance this way in my scenario, where lots of data is aggregated for a weekly summary.

CREATE view [dbo].[VIEW_FROM_FUNCTION]
as

select 
[Col1],
[Col2]
/*etc*/
from dbo.fn_YOUR_TABLE_VALUED_FUNCTION()

GO