I don't know what kind of chameleon you are getting but if its a veiled or panther...IMHO you need a phosphorous-free calcium powder such as Rep-cal to dust the insects with at most feedings.
A vitamin powder that contains a beta carotene source of vitamin A to use a couple of times a month. It might be possible to get away without this (never tried it so I only say "might") this if you gutload the insects really well.
You need a phos.-free calcium/D3 powder unless your chameleon is going to be in the direct sunlight often enough.
Reptivite has preformed vitamin A in it so it needs to be used with caution.