New Post: Installing Google Open Sans font in CKEditor

Sorry my mistake my description above was wrong. you want the open sans font so you have to put this in the css file

@import url(http://fonts.googleapis.com/css?family=Open+Sans);

and under font_names

Arial;Times New Roman;Verdana;Open Sans;

After you made the changes make sure to clear the browser cache to force the editor to reload the changed css file.