addThis to blog post

/**
  * This PHP will load only on blog post
  */

function add_this() {
	 if( is_single ( ) ) {
?>
/**
  * Follow this step:
  * #1 - visit the link -http://prntscr.com/u7ukyw
  * #2 - Add this src - http://prntscr.com/u7ul9j
  */
<script type="text/javascript" id="addthis" defer src="//s7.addthis.com/js/300/addthis_widget.js#pubid=ra-5f48848b8840c49e"></script>
<?php
}
}
add_action( 'wp_footer', 'add_this', 100 );