Ok I am not 100% sure but I had a go using the following add action to my functions.php but get a syntax error in the first line.
So here is the code snippet you mentioned on that post, would you be able to show me an example of how I would include the facebook sdk into it?
add_action( 'geodir_details_main_content', 'facebook_sdk',35);
function facebook_sdk(){echo 'hello world!';}
Facebook Script
<div id="fb-root"></div>
<script>(function(d, s, id) {
var js, fjs = d.getElementsByTagName(s)[0];
if (d.getElementById(id)) return;
js = d.createElement(s); js.id = id;
js.src = "//connect.facebook.net/en_GB/sdk.js#xfbml=1&appId=1378194292506778&version=v2.3";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));</script>