Can I add my own template to the ScratchPads?

The six built-in ScratchPad templates are currently fixed.  

As a work-around, you can create a PDF template and import it into the Documents and then annotate it using the drawing tools menu. The easiest way to import a PDF into the Documents is by linking your ForeFlight (via our website) account to a free Dropbox account (requires ForeFlight Pro).