Thank you both!
He's not gobbling it up as he did his Kirkland Chicken and Rice puppy food but he did eat some. The kibble is much bigger than the puppy food and I'm thinking that may be part of it (he's just under 3lbs). I'm going to mix a little Wellness canned food into it and see if that moistens the kibble and makes it easier for him to chew it.
The Kirkland food has more meat content than the Nature's Domain but Nature's Domain is grain free and has the healthy bacteria. Both are rated 4 stars. I looked at the list of ingredients for both and I'm still not too sure about which of the two was "better."
Is gain free better for yorkies? Is it better to feed him Chicken or Salmon? One thing I noticed while he was on the puppy food was that his poops were rather dry... Could that be because of the grain?