He is so cute and looks good to me! We have hand fed Georgie since he was having issues with his luxating patella in 2008. He has just now started to eat without being hand fed but doesn't eat out of his bowl anymore. He can be so finicky! I would suggest plain boiled chicken...I haven't met a furbaby yet that can refuse that
Also yogurt with probiotics helps give the food flavor and is great for his digestive system
As long as the vet says he isn't underweight I wouldn't worry about it.