To enable this feature in the form, go to:
Your form's configuration
Click on Add at the bottom of the list of fields
Select Signature
Select the attachment field you'd like to use to store signatures.
Alternatively, you can also navigate directly to:
Attachment field
Upload settings section
Select Signature from Field Mode.
When the field is set to "Signature" mode, it will automatically be set to only accept one file (the signature), and to use the "Contain" Thumbnail mode. These options can, of course, be adjusted to your preference.
You can make any of these three different options available to your end users:
Allow typed name signature: This will generate a signature image with a font resembling hand writing.
Allow uploaded signature image: Sign by uploading an image of your signature.
Allow hand-drawn signature: Sign by drawing your signature by hand.
By default, all three options will be enabled out of the box. However, you can disable unwanted options individually, as needed.
If you want the signature to be mandatory, you must set the attachment field as Required.