Available for paid Magpi users with the Magpi+ ("Magpi Plus") app for Android and iOS.
Signature questions allow you to draw on the screen of your mobile device with your finger or a stylus. This can be used to enter your signature, or that of a respondent, or to make a sketch. The image created will be saved and uploaded to the Magpi website, and then stored on your Dropbox account (as with Magpi photo data: read more about Dropbox integration).
Here is an example of how the signature question appears on a phone: