All you generally need to do is say "icon by name" in the icon comment field! (Some people have separate policies, but those are mainly "drop a comment if you're taking an icon" IME.) If you want to be very polite, you can leave a comment on the original post that had the icons and praise some of them, but that's not expected.
no subject
Date: 2019-08-09 07:37 am (UTC)