The exact regement is easy to figure out once you have a better understanding of why it is you are varying things up.
The four products I use are, in two categories:
[Minerals]
Rep cal with D3 (minerall WITH D3 works as well, but has less D3 content)
Minerall 0 without D3 (repcal without D3 works just as well, but lacks additional minerals)
[vitamins]
Herptivite with beta carotene as a source for vitamin A
Fluker'smultivitamin or Reptivite, both with preformed vitamin A
Vitamin D3 is required for calcium to be used by the body. Without it, the body will pull calcium from bones in order for other calcium-dependant metabolic processess to function.
D3 is normally synthesized by the animal itself. UVB radiation reacts with the animals' skins producing D3.
When denied natural sunlight, artificial methods of supplying D3 are necessary.
UVB bulbs help, but do not provide enough radiation in most cases. So, supplemental D3 is used as a, well, supplement. You want to be sure you don't overdose them, but you want to be sure they're getting enough. The "safe range" for artificial D23 supplementation varies between species, but it is generally high enough that a light dusting every week or two will not hurt.
When NATURAL sunlight is used, you do not want to give them D3. That's one reason the calcium without D3 comes in handy.
UVB bulbs will give them some D3 as well - so for the most part, I use the minerals without D3. I like minerall in addition to repcal because minerall has additional trace minerals, not just calcium. But I really trust repcal, so I use both.
I tend to dust at every other feeding, sometimes more often, it varies. I lightly dust with minerall 0 twice aweek. Once a week, I lightly dust with repcal with D3. Often, I will "cut" the repcal with minerall, so the D3 content is not so high. It's better, in my opinion, to give lower amounts of vitamins more frequently, than it is to give infrequent large doses.
Once every 10 days or so (again, I vary the heck out of this depending on diet ans other factors!), I give them herptivite. Every 2 weeks to a month (depending on diet, species, my mood at the time, etc) I give them a multivitamin WITH preformed vitamin A. I usually give one dusted cricket to each chameleon by hand. Just to make sure they have some vitamin A in their systems.
An alternative is to break open a liquid vitamin A capsule. I feel better with a powder, personally, as I've been using the stuff for 15 years and never had any overdose problems or edema* - so I know it works.
*One female veield got edema a year or so back. I had not given her any Reptivite with vitamin A for months, as my daughter dumped it all out. They didn't have reptivite, so I got the flukers stuff. It seems to work just as well. within a week or so, it was all gone and has not come back. She's laid two clutches since then with no edema.
I had a WC melleri develop slight edema. I had not given him any vitamin A for fear of edema. I gave him some, and it went away. So, now, as a preventative, I go with the 1x or 2x a month preformed vitamin A supplementation.