Thank you for your responses!  When you are referring to electronic signatures, I assume you mean: e-mailing a PDF the Form 8879 to the client, the client provides a hand-signature on the form, and then PDFs the executed copy back to you via e-mail?  Then you keep those signed forms on file. 

Yes, I looked into DocuSign and I don't think it will work for the KBA for foreign clients...

One more question, I was told ProConnect does not offer e-filing for 2016 and 2017 (only current year and two years prior).  I have to file individual tax returns for a client for tax years 2016 - 2020, do you have another Intuit software that would allow me to e-file (maybe ProSeries/Lacerte) for all tax years?