How and where would you hang a border on this wall?

In my humble opinion I would opt out on the border paper and put crown molding instead. You will get sick of the paper soon enough and it's no fun to remove the paper and them remove the residue and have to paint after that. Color the crown the same as your woodwork, it will look good and seem as part of the house. You could also add little corner pieces in a style that works for your room. I believe this also comes in a material that's not as heavy or expensive as wood, lighter to install and lighter on the pocketbook.

(then, not them)

Crown molding would be pretty expensive and not as easy to install as people make it out to be. If you like a border put at the top where the ceiling meets the wall. It is not hard to remove, ( peel, wet, scrape and wash the wall) and would cost WAY less. There are some beautiful borders available.

Have you considered using the border as a waist-high border? That would keep attention near eye level and unite the room. But if you love the border and want to put it at the ceiling, put it there and enjoy your own style. It’s your house. And post on Hometalk! ☺️

Particualarly if there is an eat-in area attached to this kitchen, I (a retired professional interior decorator) would put up your border at 34" from floor and paint a coordinating color from the border underneath. (Well, paint first, then put up the border!) Ms. Martin is right in that you would see it more at that level. Since the kitchen is white, you could use a color boost.