How do I prevent sticking to the Banneton?

I also use rice flour, specifically Bob's Red Mill White Rice Flour. It doesn't brown in the oven so it provides nice contrast on the finished loaf. I just sprinkle it heavily over the bottom and sides of the banneton, insert the dough to finish proofing, cover with a shower-cap kind of thing, and leave out on the counter to finish proofing. I've never used the linen liner that came with the banneton. After the dough comes out of the banneton, I run a vege brush around the insides to dislodge excess flour, tap it upsides down over the sink, and its clean.

I use a 50/50 rice and flour mix , and it has worked quite well. I happen to have a flour mill, but I wonder if using a coffee grinder wold world to get it fine enough

Plus one on the rice flour - I simply buy brown rice flour in my local organic shop. It is far more absorbent than other types of flours and is the best thing I have found for ensuring that even high hydration loaves won't stick to the banneton after up to 20h or so in the fridge.

Yes, rice flour. Have been using it for years with my sourdough loaves. It works.

Eric, the host from Breadtopia uses rice flour, not sure how easy it is to buy these days.