Finishing cut edges.

Evening all,

Can anyone advise how cut edges should be finished? Specifically, I have installed a DIY kitchens island and my island back board needed to be trimmed down top and one side

The top cut is covered by work top but one side needed to be trimmed. I've covered most of it by butting up to the island end panel so it looks ok, but you can see a tiny tiny slither of the end panel.

Any thoughts?

TIA.