I would recommend a 5-8% keyword density and instead of putting your links at the end of your article include keyword linked text in your resource box. It is also a good idea to include your URL spelled out, however do not waste a link on this, just spell out your URL and use your links on the keywords.

This is because some sites picking up your article for content will not pick up the links with it, you at least want your URL there so someone reading your article on one of these sites can copy and paste it into their browser if they need to.