I've noticed with my rodent bottles that some brands need to be held perfectly upright, others need a slight angle to achieve a nozzle that has the ball tip properly seated so the rats can drink but the bottle won't constantly drip. Try experimenting with that and see if it helps a bit.

One brand I have (sorry can't remember the name) instructs you to fill the bottle, put it in the holder then squeeze the bottle to "burp" it. Seems to work and if I forget it will leak slightly.