How to use Powdered Food Colors?

I am hoping to try our powdered food colors as I’ve heard they are superior for vibrancy and minimizing the risk of ruining your batter.
Am I able to add them in during the macaronage, or does it have to be into the egg whites?
I generally divide my mostly-combined batch into 2 to color halves separately. Can I add powdered coloring then?
(Pic is with my typical gel colors)