There are several good actual chin pellets as well as some rabbit pellets. Good brands of pellet include:
Oxbow Chinchilla Deluxe - can be found in some pet stores, and a member on here by the name of Sandi sells it for a good price
Tradition - you can buy this from some breeders, you can also go to their website and see if you have any dealers near you.
Nutrena Naturewise 16% (rabbit pellet) can be found at some feed stores and some members on here sell it.
Purina Rabbit Chow..I forget the full name. Several members here sell it as well.
Manna Pro Sho- another rabbit pellet. Find it in feed stores and some members sell it.
There may be several others I'm forgetting. However, the 3 I most recommend are Oxbow, Tradition, and Nutrena. I have used the first two, and I have heard good things from trusted people about the Nutrena. The only reason I stopped feeding Oxbow was I found a Tradition dealer close to my home.
No vitamin drops. As long as you are feeding a healthy pellet and hay, they do not need any vitamins added to their diet. They should be getting all they need from the pellets.