Just copy paste the following code in your functions.php file. You will find this file in your wordpress theme folder.
function insert_common_content($_common_content) {
if(!is_feed() && !is_home()) {
$_common_content.= “<div class=’wordpressapi’>”;
$_common_content.= “<h4>Enjoyed this article?</h4>”;
$_common_content.= “Check more articles on <a href=’http://images.wordpressapi.com/’>wordpressapi.com/files/</a>”;
$_common_content.= “</div>”;
}
return $_common_content;
}
add_filter (‘the_content’, ‘insert_common_content’);

Useful article related to this wordpress hack.
http://codex.wordpress.org/Plugin_API/Filter_Reference/the_content





