For veileds and panthers the feeders have to be "lightly" dusted with 2 kinds of supplements. When your chameleon is young you will use plain calcium (no d3) at just about every feeding...... if you skip one or two days a month that's ok. You will also need Reptivite with d3 twice a month. In this link I use the 12th and 23rd one. http://lllreptile.com/store/catalog...d-cage-cleaners/reptile-calcium-and-vitamins/
For plain calcium I use sticky tongues Minerall outdoor.
For multivitamin I use repashy calcium plus.
I get my boys out in the sun on weekends so don't really use a calcium w D3, plus the calcium plus already has D3 in it as well.
Edit: I dust all roaches or crickets w plain calcium to correct the calcium to phosphorus ratio. I dust with the multivitamin 1-2 times a month depending on their feeder variety and gut loading that month.
for the vitamin free calcium, I like Mineral-O by Sticky Tongue Farms. I previously used Rep-Cal for a long time and it was fine. I use vitamin free calcium most often, dusted LIGHTLY on any feeder/prey type that doesn't have the right calcium to phosphorous ratio (you want the prey to have more calcium to phosphorous, but many of the comment prey types have the opposite, so you dust to compensate).
So, you calcium dust things like crickets, roaches and mealworms, but not things like Butterworms or terrestrial isopods or snails.
How often you use a vitamin product will depend on the brand, how you gutload, whether the chameleon is outside or under UVB lighting, and the type of chameleon. I am currently using a Repashy Calcium Plus about once a week (and that's more than enough even though the package directions suggest daily use). I used to use Herptivite in the past with complete success.