how to have an electronic signature

You can add any of the following e-signature widgets  to your form:

http://widgets.jotform.com/widget/signature

http://widgets.jotform.com/widget/smooth_signature

http://widgets.jotform.com/widget/sigplus

http://widgets.jotform.com/widget/initials

http://widgets.jotform.com/widget/adobe_dc_esign_services

Here's how you can add a widget to your form: http://www.jotform.com/help/252-How-to-Add-a-Widget-to-your-Form.

Thanks