JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
To add signature and any other widgets to your form, you should check out this guide: How to Add a Widget to your Form
Now in regards to capturing signatures on your form there are several alternatives:
My suggestion would be E-Signature if you are looking for a simple way to capture a signature or Adobe DC eSign Services if you have an account with Adobe that you can use to sign the documents over Adobe.