Hey I just thought of something else you could add in if you can grow it there.. Black Oil Sunflower Seeds. You can get quite a few out of a flower head if you are willing to grow them. My chickens love it.
The general nutritional components of black oil sunflower seed are:
28 percent fat
25...
Your birds could get by with nothing supplemented depending on breed.
You don't really need a recipe.
You only have rice and flour available for dry ingredients. I am not sure how you would feed flour, as I imagine it is like baking flour and dusty. I can't see them eating this. With white...
Are you going to free range? Do they have ample room to do so?
I suggest not mixing the oyster shell in the feed you create. You don't want to force feed something that high in calcium. But I do suggest having it available on the side for the birds that need it (they will know).
Really...
What are your winters like?
Winter feeding needs to be balanced if you don't have any foraging. If they are free ranged in the warm months, they can survive off what you have to offer, but I don't know of any feed recipe that would be nutritionally complete with what you have to offer alone.