Grandpa Jim, the plastic bottle feeder I saw was being used in the fashion of an inverted jar; like a traditional mason jar feeder. They drilled some small holes in the top of the bottle cap and inverted it to let syrup form a drop below for the bees to suck.
To use the bottle feeder in a hive, they drilled about a 1 3/8” hole in the inner cover and stuck the cap end of the bottle into the hole. That seemed to be enough to keep it from tipping over. Never done it myself, so I don’t know how well it really works.
BTW… I like your feeder!