To use the 'Krrb it' button, your Bookmark Bar must be enabled. Below are instructions on how to enable your Bookmark Bar within your browser of choice.
Safari:
View > Show Bookmarks Bar
Chrome:
Wrench Icon > Tools > Always Show Bookmarks Bar
Firefox:
View > Toolbars > Bookmarks Toolbar
Opera:
View > Toolbars > Personal Bar. You must right-click the link and bookmark, then set to Show on Personal Bar which is in Details.
Internet Explorer:
Tools > Toolbar > Favorites Bar. You may also have to right-click the link and 'Add to Favorites', then put it under Favorites Bar.