This needs to replace the default Facebook code in the social addons espresso-social.php file. An API key will be needed from Facebook ( https://developers.facebook.com/ ) to replace the text XXX_API_XXX on line 26

EE Social Facebook

/* * **********************
 *   Facebook Button 	*
 * ********************** */
if (!function_exists('espresso_facebook_button')) {



function espresso_insert_to_head() {
ob_start();

// this will add the FB scripts needed and a style for the comment box that pops up.
?>	

	<style>
	.facebook-button div span iframe {
	min-width:450px;
	}
	</style>
	
	<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=XXX_API_XXX";
	  fjs.parentNode.insertBefore(js, fjs);
	}(document, 'script', 'facebook-jssdk'));</script>
<?php 

$espresso_fb_scripts = ob_get_clean();
echo $espresso_fb_scripts;

}
add_action ('wp_head', 'espresso_insert_to_head');

	
	function espresso_facebook_button($event_id) {
		//Override this function using the Custom Files Addon (http://eventespresso.com/download/add-ons/custom-files-addon/)
		global $espresso_facebook;		 

		$registration_url = $permalink . '?ee=' . $event_id; // this breaks if they aren't using pretty permalinks
		//http://kovshenin.com/2012/current-url-in-wordpress/
		global $wp;
		$espresso_url = add_query_arg( $wp->query_string, '', home_url( $wp->request ) );
		$espresso_combined_url = $espresso_url . $registration_url;
		
		// new button						
			
			$button = '<div style="overflow:visible;" class="fb-like"';
			$button .= ' data-href="' . urldecode($espresso_combined_url) . '"';
			$button .= ' data-send="false"';
			$button .= ' data-width="' . $espresso_facebook['espresso_facebook_width'] . '"'; 
			$button .= ' data-show-faces="' . $espresso_facebook['espresso_facebook_faces'] . '"';
			$button .= ' data-layout="' .$espresso_facebook['espresso_facebook_layout']. '"'; 
			$button .= ' data-font="' .$espresso_facebook['espresso_facebook_font']. '"';
			$button .= ' data-colorscheme="' .$espresso_facebook['espresso_facebook_colorscheme']. '"';
			
			
			$button .= '></div>';

		return $button;
	}

}