Have you gotten the ones in and just before High Halls? There are a couple rabbits in the dragon cliff castle, and on the small island near the Grand Knight teleporter shrine. I think there is one by the bandit's cabin just outside the harbour anti-dragon shield, to the far east.
There is a rabbit in the background during the cutscene after you give a couple malachite gems to the blind philosopher, but I couldn't find a rabbit on that ledge anywhere.
According to spif2001 in the topic
Killer Rabbit, if a low level character can kill enough rabbits to trigger the bunny's appearance, loading a high level character and killing rabbits may trigger it sooner.