Perhaps using action hooks widget is a better option. In your case, use graphene_bottom_content hook under loop.php.
If you want to see how graphene_bottom_content hook works, then visit my test site – http://test.prasannasp.net/ Those Recent posts from this test site , Latest Posts from Prasanna’s blog , Twitter Updates etc.., are placed within the graphene_bottom_content hook.
If you don’t know what is an action hook widget, luckily we have some good resources.
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