How can I sign a form that a client submits and send it back to them?

I made a contract form that requires I sign it after the client fills it out. Is this doable? I used the esignature widget and for now removed my portion for signing but would like to add it back in.

You could set up and approval type workflow as described in this thread:

http://www.jotform.com/answers/401633

This would allow you to have an approval section and give you a direct edit link to update their submission with your signature.