I have been using Repti-Vite powder + screened (I used a flour sieve to screen out the +250 micrometer shell shards) in Repti-Cal powder.
I mix the Repti-Vite with the same volume of screened -250 micrometer Repti-Cal in little plastic tub , about as much as will cover your thumb nail of each. Drop my crickets in and give them a gentle shake to dust them. This is done 3 - 4 days in a row, then I empty the left over powder into the mealworm or superworm tubs to mix with the wheatbran and swap to just Rept-Cal for the rest of the week.
I also dust the greens and vegetables with Repti-Cal each day.
Others might do things differently.