How long have you had her on the NB? It can take up to 12 weeks for some dogs to show results.
I feed raw (Natures Variety, Primal, Suzys) and just love it. You could try feeding raw - or you could try Natures Variety Instinct. You may also want to consider adding EFAs to help skin. This one is pretty balanced:
Skin & Coat Care Supplements for Dogs & Puppies: Drs. Foster & Smith Premium Plus Skin & Coat Liquid