The png doesn't show in the Hombrew Channel menu. I looked at other programs and the icon is either incorporated in the .3dsx file or is a separate .bin file. It's not really a big deal, I was just wondering if either you or other users had a premade icon.bin.
I'd never seen an icon.bin yet; the Icon for smea's homebrew channel is included in super-block-attack.smdh - you can find it here.
There are also additional meta informations like name and description included.
Can you show me a project which uses icon.bin, please?
Then I may adapt the icon to your needs.