Not to bug, but the MegaRay provides UV-A and UV-B rays. UV-B rays are needed for the beardie so they can create the vit D3 themselves (they need a lot of both as they are mainly desert animals). A lamp itself cannot create vit D3, but it helps the beardie by providing the UV rays needed. As the MegaRay is a very good lamp, it is not the only lamp which provides UV-B. If you cannot buy a MegaRay, then use an other, proper lamp for UV-B and a seperate one for UV-A (I think they are called "Daylight lamps", but always check the box).
I would suggest carefulness with adding extra vit D3 supplements, while it is not quite known how much a beardie should need (too much can be as dangerous as too little). Supplements can be helpful, as long as they are not used as replacement.