It hardly matters what else we do if this doesn't show up on the page! Use the power of filters and 'the_content' to get crucial data.

ID24 Demo 6

/*
 * Use WordPress filter 'the_content' to add sharing links into post content.
 *
 * @param $content The current content of the post.
 * 
 * @return $content The previous content of the post plus social sharing links.
 */
add_filter( 'the_content', 'id24_post_content' );
function id24_post_content( $content ) {
	global $post;
	$post_ID = $post->ID;
	if ( is_main_query() && in_the_loop() ) {
		$id24_social = id24_social_block( $post_ID );
		$content = $content . $id24_social;
	}
	
	return $content;
}