You'll need to add roughly 6.5 cups of flour, but I usually go by eye. I sometimes add a little less or a little more than this. Don't let this worry you, though. Just add the flour little by little until you have a soft but fairly stiff ball of dough that's still a bit wet and 'oily' looking. If you add a bit too much flour, just drizzle in a bit more orange juice. If it's still too gooey, add more flour.