I have a bates caprilli which is a perfect fit aside from the fact that it's sitting too low on her wither, especially when I get into the saddle. I can't take the gullet any narrower (Is narrow at the moment and works well) to 'sit it up', but have been using a folded up towel under the pommel & front of the saddle to sit it back so it's off of her withers & works well.
Anyone have experience with riser pads? I'm not too keen on using a rolled up towel in the ring!
I have the exact same saddle and had the exact same problem. I'm a ThinLine fan, and bought the "saddle fitter" sheepskin half pad with two inserts to lift the saddle of my sharkfin-TB's back. Worked like a charm.
If it sits on the wither, it's NOT a perfect fit. You can try to shim it as mp mentioned. I use a sheepskin pad with a wither cutout to lift mine. Watch carefully though for pressure points and make sure you don't end up just shifting pressure to the back of the saddle like a seesaw.