views/_comments.erb
<% if @page.enable_comments %>
<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_US/all.js#xfbml=1&appId=209177899211727";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));
</script>
<div id='comments'>
<div class="fb-comments" data-href="<%= @page.original_link_to_self(request) %>" data-num-posts="5" data-width="470"></div>
</div>
<% end %>