FYI - 

The FB Follow Button has been deprecated.  So, the close alternative that I was able to match was Like Button.  If you want the Facebook Field to work with "Like" instead of Follow, you can make changes to "pm_facebook.php".

Just browse to mod/profile_manager/views/default/output/ where you will find "pm_facebook.php".  You can rename the file with a "." (dot) in front of it (add "." as prefix) ".pm_facebook.php". This way you preserve the original file. 

Now create another file called pm_facebook.php - Edit and copy paste the following codes:

BTW, you can also download the file from https://www.myhotfb.com/file/view/2122/pm-facebook and simply upload it after you have renamed the original file.

<?php

/**

 * More info about facebook follow button: https://developers.facebook.com/docs/plugins/like-button

 */


global $PROFILE_MANAGER_OUTPUT_FACEBOOK;

$href = elgg_extract('value', $vars);


if (empty($href)) {

return;

}


echo '<div class="profile-manager-output-facebook">';

$attrs = [

'class' => 'fb-like',

'data-href' => $href,

'data-colorscheme' => 'light',

'data-layout' => 'button',

'data=show-faces' => 'false'

];

echo elgg_format_element('div', $attrs);

echo '</div>';


if (!isset($PROFILE_MANAGER_OUTPUT_FACEBOOK)) {

$PROFILE_MANAGER_OUTPUT_FACEBOOK = true;

echo <<<__FACEBOOK

<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 = "https://connect.facebook.net/en_US/sdk.js#xfbml=1&version=v3.0";

  fjs.parentNode.insertBefore(js, fjs);

}(document, 'script', 'facebook-jssdk'));</script>

__FACEBOOK;

}