MEKP in UV pigmented resin

How much MEKP do you add in pigmented resins that are UV curable to ensure that all resin kicks? I guess what I am trying to ask is what is the smallest amout that I could get away with without screwing up a board?

5cc

1/2 of 1%.

I do 2% always!

partially it is going to depend on how much tint and how dark they are, less Catalyst in lighter more translucent tints because the light can permiate more.