<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";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));</script>
Find this line:
<div class='post-footer'>
and insert this code after it:
<div class="fb-like" expr:data-href='data:post.canonicalUrl' data-send="true" data-width="450" data-show-faces="true"></div>