You are so lucky to live in such a beautiful area. One of my favorite spots in the whole world!
I don't think Kintu is too fat, but perhaps you could cut back on his food just a bit. At this age there is a lot of loose skin and it's hard to tell what is skin and what is excess without putting hands on. He should be starting to muscle up by now. I wouldn't start supplementing yet, but make sure you are feeding a good quality kibble. I give Misha 1000 mgs of Ester C, a fish oil tablet and a Vitamin tablet daily and he is fed California Natural lamb and rice with a low protein content. Seems to do well on it though he would prefer the other dogs' food which has a higher protein content. If you have him on puppy food, I would take him off it now. I personally don't feed puppy food after about 10 weeks and I have never had skeletal problems. With a heavy puppy, you need to be careful with the amount of exercise, particularly stairs and jumping on and off structures.
I looked at the pedigrees, and while I recognize some of the kennel names, I don't see any English kennels there, but then I believe the Janak dogs were sent out to NZ about 20 years ago so they probably would be even further back.
Ridgebacks come in many styles. The Europeans tend to be a heavier dog while the Americans tend to be lighter boned and "racier". The Australians are a mix because of all the different imports and the Africans are also mixed depending on what area of Africa they live.
Kintu is a lovely little dog. Reminds me so much of Zack.
Caroline