can i add flicker url in my gig?
Yep. Earlier I put samples of my designs for one of my gigs using external urls but fiverr customer support advised me to use youtube or flickr instead. Problem was my designs were interactive so Flickr wouldn’t do it for me.
But yeah. Flickr is allowed. Not sure about other imaging sites though.
You can read the TOS to find out what you can and cannot do. I know you can reference a YouTube account but not sure on Flickr.
I have seen some gigs having flicker link on them, i think it would be ok if you are sharing that link to provide samples to your buyers. To know for sure i suggest you contact fiverr support, and ask them this question.