That plugin is the one I’m using on the demo. As you can see here – http://demo.appfinite.com/followme/ it’s responsive and doesn’t get distorted. If you can’t find any other plugins, than you can manually do it by using a tutorial. I did a google search and came across a few –
http://mobile.smashingmagazine.com/2013/07/22/simple-responsive-images-with-css-backgrounds/
http://www.onextrapixel.com/2012/03/02/using-css-background-size-responsively/
http://stackoverflow.com/questions/12609110/responsive-css-background-images
…and there are many more you can find by searching “How to make background images responsive”. Although, it should work with the plugin I have in the Read Me….I’ve never had an issue with it on the sites I’ve tested it on.