Perforator
Select from main Menu: Tools > Perforator.
New panel PERFORATOR will appear.
Serration control:
- choose stamp image
- select image
- unselect image
- zoom 2x
- actual size
and
- change units
- change background
- cancelMove the stamp image with mouse so that the serration of stamp matches the perforator.
For better control choose 
Select from main Menu: Tools > Perforator and cancel Perforator panel selection.