I dust mine every time or sometimes every other time with regular vitamin powder. However you should make sure that you dust with the calcium with D3 once or twice a month. All other times you dust your crickets should be vitamin powder without d3.
Are we talking about a multivitamin? A multivitamin like Herptivite can be used a small number of times a month, about 2-3. The same with any calcium with vitamin D3, it should be used very sparingly.
If we're talking about a plain calcium with no vitamins added then yes, you can use that at every feeding or so.
I have a juvenile Senegal female. I use the Flukers liquid vitamins in her water. I have Rep Cl calcium with vitamin D powder. So i should be dusting every time? She eat about 6-7 crickets every day.
I wouldn't use any vitamins in her water, you wouldn't want anything like that to get in her eyes, for example.
It's better to buy the separate supplements, at least a PLAIN calcium (no vitamins at all, just calcium mineral) and then a multivitamin powder. You already have the calcium with D3, so you can use that about twice a month.
The PLAIN calcium is the supplement you can use at every feeding, but the other two are best is used more sparingly (about twice a month, each.)