Thank you for your post.
In FileMaker Go 13, the script step "Insert from Device" was introduced. One of the options allows you to specify capturing a Signature. For complete information, see FileMaker Help:
Let me know if you need additional clarification.
Many thanks. This is just what I need. Unfortunately, I'm developing on FM12 Pro/Server and it doesn't seem to be available. Eventually we'll upgrade and when we do, I'll utilize this addition.