Royalty Free Images Use

So, I've been cleaning up my Authority Site and trying to basically make it 100% legal in the sense that I'm not using Google images. I just started using Fotolia and their TOS is incredibly confusing. I don't understand if I am allowed to post the Medium size pictures I downloaded onto my website and if I have to give credit to the photographer? Anyone have a general rule of thumb for using Royalty Free images on authority websites?

-Hopeful

I'd give reference to the image creator/owner in the caption to be safe. Usually that's enough to cover yourself but sometimes there's more to it.
Of course I know nothing of Fotolia.

Also add a "Removal" request section on the site as well.

Thanks guys, so I added photo credits for both the photographer and Fotolia in the caption. I will update my TOS section on my site with something about photo removal as well.

Also, to go the extra mile, I edited the royalty free images that I uploaded to lower their pixel ratio (i.e. 1500x800 vs 800x500) so now the max photo size a user of my website can download is much lower, so I think I'm protecting the images a little better that way.

More advice would be appreciated. I'm going to be contacting Fotolia sometime during the week to see if I can get any more answers.