<<Disclaimer: Verify this information before applying it to your situation.>>
 
Here's my recipe for bread using sour dough in a bread machine. I have a
Welbilt 1 lb. machine, but I'm sure this can be modified  for other machines.
You can also pour this into a regular bread pan, let it rise once, and
bake it in the oven. (The dough is runny - more like batter than dough.)
 
Ingredients include GF flour modified from Betty Hagman's formula. I mix
up a large container of it and dip into it whenever I need some:
6 cups brown rice flour
2 cups potato starch flour
1 cup tapioca flour
1 1/2 teaspoons xantham gum
 
Sour dough:
Mix 2 cups GF flour
    2 cups warm water
    1 teaspoon GF yeast
in a glass or plastic bowl
 I let it sit (lightly covered) for a day or so at room temperature;
 after that I keep it covered in the refrigerator. Whenever I
use a cup of it, for example, I add a new cup of flour and one of water. I
never let it go more that 4 or 5 days without adding new stuff to it,
even if I haven't used it. I add this to any recipe that calls for
buttermilk or yoghurt. It makes great pancakes and waffles, moist cakes
and breads,  flaky biscuits (are you drooling yet?)- just use any regular
cookbook and your imagination.
 
So here's my bread recipe:
 
Add to the bread machine bowl in this order (no matter what the
directions say):
        1/4 cup oil (or melted butter)
        2 T honey
        1/2 cup starter
        4 eggs
        1 teaspoon salt
        2 teaspoons yeast
        2 cups GF flour
 
Start machine. That's all.
 
Caution: Results vary depending on how energetic the starter is. If it's
old and tired, the bread doesn't rise much. If it's young and
enthusiastic, the bread might overflow. You have to learn by trial and
error to become acquainted with your starter and know when you might want
to add more or less of it. I look at as an art, not a science. I've had
my share of disasters, but I enjoy the challenge, and I especially enjoy
the moist, fragrant results that I usually get. Don't be afraid to
experiment.