Those look like a meat rabbit, hence their mass/size. My guess is Californian's. They should be fed 1/4 to 1/2 cup of pelleted food a day per 6 pounds of body weight when they have reached adulthood(7 to 12 months of age). Since you free feed pellets you will slowly cut back to the 1/2 cup mark and see if they need to be cut back further.
Free feed timothy or grass hay and slowly add rabbit approved vegetables to their diet ultimately you will feed 2 cups of chopped veggies(ie basil, alfalfa srouts, escarole, green peppers, mint to name a few) a day per 6 pounds of body weight. Hay, veggies, pellets, treats (fresh fruits liker papaya, apples, raspberries and strawberries) in tiny amounts-2 oz/2 tbsp a day per 6 pounds of body mass)
Ideally they would also be on a timothy pellet, but for meat rabbits I like to keep them on an alfalfa pellet or a good mix of alfalfa/timothy blend pellet. I, myslef, like Heinold pellets over Purina. The protein is the important part to watch. Too much protein will allow a rabbit, especially as meat variety, to get too fat. So I free feed hay as much as they want and watch their alfalfa intake with a pellet that I can control.
Not knowing thier age and breed it is hard to determine the weight they should be. I would weight them and if you know the age and breed, look up the breeds group/association and see what they are supposed to be. Then either increase or decrease their diet.
