When drinking, how many ounces of a high fat formula (50cal/ounce) can a child (small6yo) digest/process per hour? where can i find info? references?

Formula for 6yo?: 6 year olds don't drink formula. Do you mean a nutritional supplement like pediasure? If so, you should be using this only on the advise of your doctor. The best nutrition is from a good diet, not from supplements. When supplements are required , the doctor making the recommendation will give you an exact amount. Please don't feed supplements without a doctors advise. Feed food instead.