Have you tried adding tripe to his food? Most finicky dogs love this stuff! (That way you could get him to finish of the Wee Bit)
It also has good benefits:
I noticed that my dogs gobble away more when I add a new ingredient or flavor rather. So I stocked up on canned food in several different flavors & rotate 2 cans until they are gone.
I have 2 picky eaters, to ensure that they CANNOT they cannot pick and choose what they like - I pulverize the kibble with the chopper attachment on my hand blender. This works ideally if you add it with canned food or an liquid supplement -- you could even add water. I started doing it for my 2 Havs that aren't picky eaters because when I started supplementing them with Salmon Oil it seemed more of it to end up in their beard! Ahh, what a great lingering fishy smell!
Might also try using one of Honest Kitchen's all life stages dehydrated formulas as a topper 1 TBS or substituting half his food with it:
* Love this stuff! Yes, there is a bit of sticker shock when you look at the cost up front. I incorporate into my adult dogs more as a food topper/gravy something to spice up their food. (Actually cheaper than buying IAMS dog gravies in the long run - not too mention healthier). They love it! A little goes a long way. I only add a Tablespoon to the adults dogs daily meal. They suggest rehydrating with 1 cup with 1 to 1.5 cups of water. To increase our dogs water intake I use 2 cups of water to 1 cups food. Makes it last even longer! It lasts us 10 days and thats feeding 4 dogs. So, imagine how much further it'll last if you only have one or two small dogs
We have yet to make a dent in the 10lb bag! Also, you might want to make a small batch as unused portion should be used within 48 hours. Or, freeze the other portion..*
I like Wellness Super5Mix Just for Puppy - all of our puppies love this stuff!