Kibble is supposed to be "nutritionally balanced and complete" (I don't buy it for a second, but that's another story!). I wouldn't recommend a multivitamin with kibble - it may cause an excess of certain things - but if the dog is under stress, Vitamin C, Vitamin E, or Vitamin B may be added (I'd check with a vet and/or nutritionist first, because it really depends on the kibble you're feeding and what supplements have been added to it).