Do you know how to use the new Apex Toolkit Docusign API to transfer data to a custom field (a Salesforce merge field)?

This is the instruction I've been following: https://developers.docusign.com/docs/salesforce/how-to/send-envelope/

However, there are no examples of custom fields being filled with Salesforce data. I attempted to use a custom field class, however it only has read-only properties.

What is the best way to send salesforce data to a template document?


Nama
 

I am coding using Salesforce Apex and DocuSign API. Here a part of my code :
 

DocuSignAPI.Tab tab100 = new DocuSignAPI.Tab() ;                        
tab100.Type_x = 'Custom' ;     
tab100.RecipientID = 1 ;                           
tab100.DocumentID = 1 ;                           
tab100.PageNumber = 1 ;                           
tab100.XPosition = 40 ;                           
tab100.YPosition = 40 ;

Unfortunately, I try to use other field name like "Font, FontSize" but it is not recognized : I got this message "Variable does not exist : Font".

Thanks
 

I am coding using Salesforce Apex and DocuSign API. Here a part of my code :
 

DocuSignAPI.Tab tab100 = new DocuSignAPI.Tab() ;                        
tab100.Type_x = 'Custom' ;     
tab100.RecipientID = 1 ;                           
tab100.DocumentID = 1 ;                           
tab100.PageNumber = 1 ;                           
tab100.XPosition = 40 ;                           
tab100.YPosition = 40 ;

Unfortunately, I try to use other field name like "Font, FontSize" but it is not recognized : I got this message "Variable does not exist : Font".

Thanks