Simple, just the URL in the link off site box-thing, and then where it says avatar dimensions, just set it to where the image is not distorted but below 120x120 pixels, please. Like mine,
here's the link, as you can see, much bigger than 120 by 120, so, I just scale it down with simple division to where the ratio of height to length is the same, just with numbers under 120, and put that in the avatar dimensions areas, hit submit, budda-bing, budda-boom, you got it.
At least, that's how mine worked.