An idea I had was if you killed someone, a little green tick would appear on the right or below your reticule, and if they escaped then a red X would appear in the same place. It would just tell me if I got the kill when they ran off the edge, or away. It would be toggleable, and also toggleable for position and type of kill:
Tick for:
All kills: Yes
(Fall kill: Yes)
Etc.
Position: Below shields
Would this be a good idea?