Hi, If the puppy has been bred by a reputable breeder then they are the best person to advise on how the puppy should be fed. Its always best to feed a new puppy exactly the same way that he is used to. unless its totally unsuitable, at least for the first week/10days to help him settle in easily.
If you change his diet it must be done very slowly, over a couple of weeks as to start him on something completely new is asking for a tummy upset. Contact your breeder and ask what they are feeding him on, so you have plenty of time to order it if its not easily availble in your area. Come back here and post what is if you like. There are many, many suitable diets for puppies. When you pick your puppy up, feeding should be discussed at length with you by the breeder and you should receive a detailed diet sheet along with his KC registration papers and pedigree. :-)
Just to add - Along with diet sheet, pedigree & registration papers, you should also receive from the breeder vaccination certificates and microchip certificate (if pup is chipped).