Sketch Field Type can be used to capture signatures and can also be used to annotate images or drawings. 

Configuring the Sketch Field Type

Simply drag 'n drop a Sketch Field from the left-hand toolbar onto your Form page, then configure it using the right-hand properties panel.

Capture Signature: Displays an inline drawing area for the user to enter their signature.

Static Background: Upload a default image for use as the background for sketch drawing.
Useful for scenarios like marking out issues on technical diagrams, annotating floor plans and other outline/blueprint type images.

Dynamic Background:

Define a calculation/formula that will dynamically populate an image into this field.

e.g. CONCAT('', {{myfield}}, '.jpg')

e.g. {{mydsfield[2]}}

Is Personal Data: Indicates that data captured in this field may contain personal or sensitive data, which in turn can be anonymized when exported from the platform.
NOTE: Use of this option does not grant or imply additional security, protection and privacy of data.