Hi!
Vitamins and supplements are not needed, if the rabbit gets all the nutritional elements his organism needs from a healthy, complete diet. This kind of additional intake of vitamins, minerals etc. is only correct in case of a compromised health and a vet prescription, based on a blood work and a full evaluation on which elements are missing, therefore, should be additionally administered.
I know that pet stores promote this kind of things, but it's wasted money on a healthy rabbit, their purposes are purely commercial in selling multi-vits and the rest.
Marietta