Sorry - I'm just now checking in on this thread - this information was in the link I provided in my earlier post - which also gave tips on how to feed the babies....
How much to feed?
The following information on feeding quantities are from the House Rabbit Society FAQ on Feeding Orphaned Baby Rabbits, which is an excellent source of additional information on this topic.
# Newborn to One Week: two - two and a half cc/ml each feeding (two feedings per day).
NOTE: Many newborn mammals cannot urinate/defecate on their own. The baby bunnies will require the stimulation of the mother's grooming tongue on their bellies and ano-genital region in order to release a stream of urine and those pinhead-sized poops. Fortunately, you do not have to use your tongue.
Use a cottonball (or even a very clean and disinfected fingertip) moistened with warm water, and gently tap/rub the urogenital area until you feel the baby's abdominal muscles tense and get that rewarding stream of warm pee! (Now you see why we suggest you use a towel on your lap.) Getting a urination response may take 15-20 seconds of stimulation, or even more. Many sources recommend doing this before feeding, and if it works--fine. However, sometimes the stimulus of a full stomach makes this easier. If the baby will not urinate before feeding, try again after feeding, and you will likely get a good response.
Failure to stimulate the babies to urinate/defecate can in the death of the baby (the bladder can actually rupture if it is not stimulated to empty!), so be sure you do this procedure diligently, gently, and patiently! It may take a couple of weeks before the babies are able to urinate and defecate on their own. Watch for signs of redness/irritation around the anus and uretrhal opening, which indicate you are stimulating too vigorously. Back off on the pressure, and apply a bit of soothing calendula ointment (available at health food stores) to heal the irritation.
If the feces come out liquid or "smeary", it's a sign of potentially serious trouble. Consult your rabbit-experienced veterinarian at the first sign of diarrhea, as this can be fatal in only a few hours in a baby rabbit.
# One to two weeks: 5-7 cc/ml each feeding (two feedings per day). The amount will depending on bunny, and may be much LESS if the baby is small.
NOTE: Do not allow a baby rabbit overfeed at one sitting! Once a baby learns the Turbo Suck (tm), he can suckle so quickly that it's possible for him to ingest a volume too great for his little tummy. Although it's unlikely for the stomach to rupture, stretching it too taut can cause pain, gas, and make the baby sick. It is better to underfeed slightly than overfeed. If in doubt, let the baby rest for about a minute after feeding, then offer the nipple again. This gives time for the stretch receptors to respond and let the baby know he's really full.
# Two to three weeks: 7-13 cc/ml each feeding (two feedings). Domestic rabbits' eyes open at about 10 days of age. Start introducing them to timothy and oat hay, pellets and water in a shallow dish.
# Three to six weeks: 13-15 cc/ml each feeding (two feedings) As always, quantity may be LESS depending on the size of the rabbit.
NOTE: At the age of about three weeks, babies will begin to experiment with solid food. Not only is it important to continue enriching the formula with colostrum, but at this stage it is time to inoculate them with normal rabbit bacterial flora from a healthy, parasite-free adult rabbit. Start to scout for a potential cecotrope donor when you first take the babies into your care. When they're about 2.5 - 3 weeks old, obtain a fresh cecotrope and mix it into a small quantity of formula. You will probably have to feed this as if it were medicine, as most babies do NOT enjoy this "special" formula. But it will help to establish their normal flora at a time when the stomach pH is likely not to interfere with proper colonization of healthy bacterial flora farther down the intestinal tract. Inoculation for 2-3 days in a row seems to be sufficient for establishment of normal flora.