If you have not yet read the base FCG layout guide instructions, read them here.
The same principles apply and this guide will only address the differences in marking and cutting for the stock.
Differences from other drill guides
All holes on the PUF guide remain the same as the standard layout guide with the exception of the rear trunnion, possessing extra holes for the underfolding mechanism and differing position for the rivet holes.
Here you can see the comparison between the extra holes and the desired end result. When marking all your other holes for the FCG, just mark these like you would any other.
Drill your latch holes (outer two) as normal, using measurements from your parts kit as a guide to ensure a good fit, drilling undersize and filing to fit if needed.
When drilling the center hole, use your trunnion as a guide for size, step drilling or otherwise removing material until slightly undersize, and then carefully filing out the remaining material to match your trunnion by hand, ensuring a nice fit.