I like it when artists put their @ on their art. maybe some people don't. but I like how it's pre-credited.
I personally believe most people don't "share the source" because this means keeping track of two things, and this adds friction. So I'd say adding the author's name on the image itself in some place where it's not intrusive is the way to go. Now, of course there are people who will remove attribution from the image itself, but this is a minority and not really worth catering to.