As a general rule, 2-3 oz / lb of body weight / day, minimum. Use an IV set up that is 10 or 15 drops / ml and a 16 or 18 ga. needle so that you get it in her fast, so the treatment doesn't last so long.
If she is a mature doe, 80+ lbs, give her a liter of lactated ringers (LRS) at least 2/day, maybe 3 or 4. It also comes in a 5 liter bag, for horses or other large animals, that you could run to her sub-cu in 2 or 3 treatments throughout the day. It will blow up like a balloon under her skin. As soon as the balloon is gone, run her some more. Each side of the neck has the best absorption, she will look like she has football pads on. Some will settle down under her brisket, not to worry.
She will use all she needs, and pee out the rest. You can't overdo it when giving sub-cu. Warm it up so that you don't require her to use energy maintaining body temp.