This plugin is the only Pinterest button on images plugin I could get to work, but it also breaks my theme.
When activated, my sidebar displays at the bottom of the page and other formatting problems occur. Also, it sometimes puts 2 pin it buttons on a single image.
When I disable the plugin, everything returns to normal.
It is currently deactivated, but the site in question is this one: http://prettytastesbetter.com if you want to look at the theme and see if you can figure out the issue.