In JA Fixel template, we add the following code which displays Facebook comment in article layout of Joomla content component. If you want to apply the same, you can open this file in template folder:
templates/ja_template_name(default_template)/html/com_content/article/default.php
And add following snippets:
<?php if($tplparams->get('tpl_facebook_comment', 1)): ?>
<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<?php echo $tplparams->get('tpl_facebook_appid', '') ? '&appId=' . $tplparams->get('tpl_facebook_appid', '') : '' ?>";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));
</script>
<div class="fb-comments" data-href="<?php echo JUri::getInstance()->toString(array('scheme', 'host', 'port')) . $this->item->readmore_link ?>" data-num-posts="10"></div>
<?php endif ?>