[dawn27]

Wow 1 lb is tiny. My pups averaged a pound when they were 4 weeks old. The runt of my last litter at 10 weeks was just shy of 2lbs. At 5 months old turning 6 in a week she is still very small and weights 2.7 lbs.

Is there any chance he is younger than what they say?
Do you have his registration papers?

Food wise you really should be feeding him the same type of food he was on at the breeders. Nothing about his diet should be changed this soon. You need to give him a couple of weeks to adjust to the transition to his now home and surrounding before you change it and be sure to do it gradually by mixing old with the new in percentages until reaching 100% of the new food. Changing it this soon will cause him to be finicky and stubborn about eating as you are finding out. Or worse stress. If you feel that he is not eating, try to add a little can puppy food to it to give it some added flavor. Preferably the same brand as the dry kibble.

At his size he needs to eat at least 4 small meals per day every 4-5 hrs up to a few hours before bed time. He's so tiny and cant handle a large amount of food per feeding so it may be best to feed several smaller meals 4-5 making sure to monitor how much he is eating. So that you can be absolutely sure that he is eating. He will be fine thru the night and can last til morning. As long as he is eating, getting plenty of rest there shouldn't be a reason to substitute with Nurical or any other sugar supplement unless absolutely necessary and is showing signs of low sugar.