My resident cat won’t stop attacking new kitten over 1 month!

Hi all! I need help! About a month ago I adopted a new kitten. We tried to introduce her slowly to our resident cat. We had a few failed attempts (I fear that we were going too fast for her) so we went back to square one of keeping them in other sides of doors. We then moved to a screen door, scent swapping, and now we allow them to be in the same room while being supervised.

Our resident cat (3 y/o spayed) has stopped hissing but continues to “hunt” the kitten (4 m/o spayed). It’s to the point where neither of them can do anything else while in the same room with each other. When our resident cat attacks her there’s loud screaming. There’s never any physical wounds. We try to make a loud noise but it doesn’t work until we get the spray bottle or physically take the resident cat off of her. The only time they can tolerate each other is when we feed them treats next to each other.

We have tried Feliway diffusers and sprays, over the counter calming supplements, calming water drops, and now gabapentin with the resident cat. Literally nothing works and I’m at wits end. I don’t want to get rid of the kitten because we’re attached to her. We just want them to tolerate each other! Please help!!

*they have their own litter boxes, food, high perches, and toys