People I’ve fished with have different methods they use, my preferred method is to kill the fish as soon after it comes on board with a baton.
Firmly hit the fish on top of the head just back from the eyes, you may need to do this a couple of times.
I personally don’t like the idea of a fish dying slowly in the chilli bin because I think it’s cruel. I love kingfish and want to respect the life I’ve taken by not letting it suffer a slow death.