and not to "jump on", but it is nearly impossible for the average chicken owner to reliably provide a nutritionally complete and well balanced feed meeting the optimal nutritional needs of a modern chicken. For a host of reasons completely out of the owner's control. Even if they could, without the economies of scale enjoyed by commercial mills, they can't do so at a cost savings.
The more I know about feeding birds, the less inclined I am to attempt to do so on my own - though I do engage in some "educated risk taking", I readily acknowledge that there are no guarantees, that my methods are not for most, and I do NOT recommend them.
BYC members have helped a few in rare or unique circumstances with at home feed recipes - but those persons were already successfully engaged in commercial scale farming, lived in remote locations with no commercial feed option, or were attempting a substitution of ingredients with a more readily available local grain (typically). With no guarantees, merely a start there, and adjust based on experience and observation.
My advice, like the others above, is don't attempt it. But if you want to educate yourself, I recommend you start with J Rhodes' recipe and flock management, then research/read/study until you understand why he uses the ingredients he does, in the quantities he does. You want to may particular interest to the research on poultry and B6, B12, Methionine, Lysine, Calcium sources, Phosphorus, Ca : P ratios, Selenium and acceptable fat levels. That should lead you to yet more more research and other topics that need understanding before you can begin to put together an optimum at home feed. In Theory.
In Practice, with no way to assay the actual nutritional contents of the ingredients, its educated guess work, more akin to stereotypical hedge witch of the dark ages than a scientific formulation.