It works and you can in fact set it to open your PDF with any program you like (not just Foxit). However there is an additional step for Linux users which the instructions do not make clear: you will need to open the add-on preferences and change the add-on path from "Foxit Reader" to FoxitReader. Also, the option to open in Foxit with left click does not reliably work; some PDF links do open with it, some open in Firefox.