Feeding a pom

Question
My friend asked me to take care of her pomeranian, Romeo.

The food we feed him is supposed to be natural.  All of the other dogs (we are taking care of four including Romeo)  eat the food.  Romeo eats it but in little bits. I feed him a cup a day and he doesn't finish it.  Is it because of taste?

Also he has lost weight.  I have never had a pom before so I dont know if he's too skinny (he was pudgy when he came) and I dont want her to think i'm starving her dog.  I can feel his ribs and spine a bit and a slight outline when he's lieing down and leg bones but nothing else.  Is this too skinny?  If so how do I get him to eat more?  It is a natural food...Nurto I think (my parents threw the bag away)  

Answer
If you are concerned you can add plain yugurt or cottage cheese to his diet.  You can supplement with boiled chicken or raw ground meat.  Depending on how long you are to care for the dog and if he is loosing a lot of weight it may be something else health related and he may need to see a vet.

Best of luck.

-Trish