I agree that she is probably allergic to something in her dog food....dogs tend to be allergic to corn, wheat, soy, and beef, all or most of which are probably in the food you are feeding her. I would first try switching her food to something off
THIS LIST.
If switching her food doesn't get rid of the dandruff (give the food 2 months to work), then there are a variety of things you can try. I would add some Omega fatty acids to her diet. You can do that through
Missing Link Supplement or
Grizzly Salmon Oil.
You can also try switching her shampoo to an oatmeal-based shampoo. I would also start using a conditioner.
GOOD LUCK and CoNgRaTuLaTiOnS on the new family member! She definately is a beauty.