do not believe so
— Mike Mearls (@mikemearls) August 18, 2018
That sounds like the rules are vague and up to DM discretion. No, it means I don’t have a book with me to check! It most likely wouldn’t work, since rituals don’t require you to expend a slot, and I believe that is a requirement for the ring.
— Mike Mearls (@mikemearls) August 18, 2018