The number of Font Awesome fonts available in rock ocassionally update and are sometimes out of sync with all of the font currently listed on the Font Awesome website. To find a font, while working on content in Rock, you currently need to leave Rock, go to Font Awesome's website, find a font and hope it is implemented in Rock.
This plugin cuts that process down significantly. A page will be created under CMS Configuration. When this page loads, the contents of the bootstrap.css file that is linked in the header is processed and the icons available in the css file will be displayed. A text box for filtering the icons will help you find the right one, and you can select the size icon you want to use. When you found the font you want to use and selected the size you want, clicking the font will copy the <i> tag of the selected font to your clipboard for your use.