Sue I would be very hesitant to feed ANY Science Diet product, like Karen said, it is a money maker for the vets. Read the ingredients on the label and also read the Dog Food Adviser reviews at this link;
http://www.dogfoodadvisor.com/dog-food- ... adult-dry/ Part of her problem may be due to medications. I would also stop the Proin as one of the side effects is loss of appetite. The original problem that caused the incontinence may have resolved by now. When one of my dogs had a small leakage as she aged the vet put her on a hormone for a short time which fixed the issue.
At this point I would give her what ever she will eat that isn't too rich. Be sure to boil the chicken, I only use the skinless breast meat, thighs seem to have more fat, if your giving rice don't give whole grain, they can't digest it. I don't give rice for too long as too much can cause constipation, plus of course there is the arsenic issue now. Plain pumpkin is always a good addition and most dogs like it. Also even though I cringe at the additives, baby food will sometimes encourage appetite, get a variety of small jars and see if she likes any. Lean hamburger might appeal to her, boil and drain off any grease.
This link will give you ideas for finding recommended food.
http://www.dogfoodadvisor.com/best-dog-foods/Sure hope she eats soon, I know how upsetting this is for you. (((((HUGS)))) for you both.