The standard feeding ratio for heritage breeds is 0.33/lb per feed per bird per day, or 53 lbs of feed per week, so you need to be feeding a little more than 1 bag of feed per week.
The recommendations for breeds like the black sex-link is only 0.25/lb per bird per day, for only 40 lbs of feed per week.
HOWEVER, I do not find this to be true. I feed a minimum of 1/3 lb per bird per day, and almost all of mine are sex-links. Sometimes, they eat less, sometimes they eat more, and I feed according to what is left in the morning, plus more when it's cold, or at a time when I know their reproductive systems are "gearing up" for laying in the spring.
I feed a minimum of 5250 lbs of feed per month to my flock, based on the 1/3 lb/day, and then ADD stuff like cracked corn, if I want the eggs to be more yellow, or alfalfa hay, if I feel they need more nutrients, plus they "steal" my horse and sheep feed, when my livestock are feeding, and they're free-range, so they forage all day.
Therefore, for your birds - feed them a minimum of one bag per week, plus all your household scraps, and an extra scoop of layer ration per week.
Rachel, TX