First off I don't know what font it is & second I have never applied a system font. I'm rooted, S-OFF running stock with goodies android 4.3 and will prob be moving to OMJ's Bad Boyz 4.4 soon. I'm guessing I just use something like Font Installer from JRUMMY apps? I do want to be able to go back to stock with ease if I don't like it. I can search as well but I still don't know what font is in the screen shot if someone knows.