Our beardie gets offered food once every day and we always dust the bugs with calcium that includes D3, and once a week we also dust them with Reptivite. Our beardie won't eat his veggies either, except squash if we hand feed it to him, and once in a great while a small bit of greens with much coaxing :roll: . He almost always eats some crickets or roaches, which we dust, and occasionally we splurge on hornworms, which he almost never refuses.
He has a Reptisun 10.0 T5 HO tube lamp that sits on a screen top, which, according to the meter, cuts out about 30% of the UV. His basking platform is about 10-12 inches from the heat and UV lamps. We have never had any problems with Vitamin D3 deficiency or excess, and his little skeleton is in good shape.
Just another example. I guess there's more than one way to do vitamin supplements. :?