Some Yorkie coats are silky. Some are cottony. My two have cottony coats - they are soft and thick. They are shiny in the sense that they are not dry, but they are not "silky" like most Yorkies.
Anyway, my point is that sometimes even with the best foods your Yorkie will not be as silky as other Yorkies.
HOWEVER - I agree that Canidae is a fantastic food. It has more Omega 3&6 than a lot of the other foods out there which is good for your dog's coat. Plus, it's not one of the "designer" foods so it's reasonably priced. We just switched back from Innova Evo because I expected the Evo to be so much better, and it wasn't. It was fine, but Canidae is a bargain and they are a really good company that I trust.
You can't get it at Petsmart. Check out
www.canidae.com to find a store or you can buy online. We've used the All Life Stages, Lamb & Rice and this time I bought the Chicken & Rice.