I would also urge you to try some rice bran, again if you can find it, as it is useful to bulk simple food and
has several advantages to dogs in renal failure
Small meals more often is the way to go, if he'll have anything. You could also try making a broth with the meat, rice bran, boiled white rice, a spoonful of chopped boiled or steamed cabbage - just chop finely and boil up, let go cold and see if he'll lap it up. Broth is useful because it gets additional fluids in him.