This is a good question because I have never seen a detailed explanation :<0)
The thick side is where I start. Calipers on the razor where I want it to come to rest. Sand the wedge to get around an 1 1/2" of spread between the scales on the pivot end. This can vary depending on the material of the scales. Test pin and see how the razor moves. It should get tighter when the blade is parallel with the scales. This helps keep the scale from moving when your honing and stropping.

Now there are guys that have been doing this a lot longer than I have but this is what I have discovered on my own.
Will be watching to see what I may be missing !