Note: only users who are marked "Is Doctor" (and are actual doctors, of course) in admin are need signatures.
Add a signature to your user profile
To add your signature:
Log in to Shepherd
Click your name on the left side of the screen
Click the 'Add Signature' button (pink box)
Press and hold the mouse, then drag the cursor in the blank space (blue box) to create your signature
Click 'Save Signature'