There is controversy over whether chameleons can convert beta carotene into preformed vitamin A or whether they need preformed vitamin A as part of their diet. I usually trade off between the two types types of vitamin A. Repashy Calcium Plus is an example of a supplement that contains preformed vitamin A, and Rep-Cal Herptivite is one that contains beta carotene.
Unless there is a clearly identified problem I would only use standard supplements like the ones I mentioned. Vitamin A deficiency usually first shows up with closing of one eye and no other signs of problems or infections. If your vet said there is a not a problem and he is not closing his eye, I would not worry about vitamin A deficiency if you are using proper supplements and gutloading.
If at some point there is a problem, that brand of vitamin A looks good, but you would want to carefully follow the instructions in the thread I linked. My veiled had the symptoms of vitamin A deficiency and they went away about a week after following those instructions.
