Prepare the Flange
First things first, it’s a good idea to take one of the bottles you plan to use with you to the hardware store. Yeah, you may raise some eyebrows, but it’s the easiest way to know if your flange will fit.
IMPORTANT: It’s ok if the flange fits a little loosely in the bottleneck. You can snug it up by wrapping the flange in teflon tape (see nearby photo).