I have just added a hole beneath the keyring loop to allow a split key ring to move freely.
The original file is great if you scale it up a little, but in order to keep it keychain sized this hole makes it work way better -especially if you use a slightly fatter key ring.
Print right side up, and laying flat on the bed. Support will build up on the inside and the top layers will build on this. Remove support with alligator nose pliers.