Well I think that might be the problem. RAW is not designed to be eaten ALONG with kibbles. Their bodies digest differently so if you are not consistent, your pups is not consistently getting what he needs in regards to nutrition if you feed kibble then raw then kibble, etc. (Some dogs are able to adjust, but its not recommended)
In any case, can you post some pictures from the front and side (while your dog standing up) and we can offer opinions on if he really is "too lean" or not.

You can upload from your phone to photobucket or from a computer and paste the code in here.
Do you have a place you could set up something like this, my boy loves it and can go for as long as I allow him too:
[URL=http://www.youtube.com/watch?v=Sgw694IPd78]Mel being a goof on the spring pole - YouTube[/URL]
or when the weather is bad:
[URL=http://www.youtube.com/watch?v=YLWCPRgCDww]Mel on the treadmill - YouTube[/URL]
My pup LOVES keep away, you just need to get someone to help you keep it away :)
[URL=http://www.youtube.com/watch?v=xu7MV2gQP-U&feature=relmfu]Mel backing it up - YouTube[/URL][/quote]
OMG, Mel is soooooo cute! Anyways, thanks for the advice and I will post pictures soon!