<!-- ADD THIS TO YOUR FUNCTIONS.PHP FILE -->
/*===================================================================================
 * Add Author Links
 * =================================================================================*/
function add_to_author_profile( $contactmethods ) {
	
	$contactmethods['rss_url'] = 'RSS URL';
	$contactmethods['google_profile'] = 'Google Profile URL';
	$contactmethods['twitter_profile'] = 'Twitter Profile URL';
	$contactmethods['facebook_profile'] = 'Facebook Profile URL';
	$contactmethods['linkedin_profile'] = 'Linkedin Profile URL';
	
	return $contactmethods;
}
add_filter( 'user_contactmethods', 'add_to_author_profile', 10, 1);

<!-- ADD THIS TO THE SINGLE TEMPLATE -->
	<!--BEGIN .author-bio-->
	<div class="author-bio">
		<?php echo get_avatar( get_the_author_meta('email'), '90' ); ?>
		<div class="author-info">
			<h3 class="author-title">Written by <?php the_author_link(); ?></h3>
			<p class="author-description"><?php the_author_meta('description'); ?></p>
			<p>Website: <a href="<?php the_author_meta('user_url');?>"><?php the_author_meta('user_url');?></a></p>
			<ul class="icons">
				<?php 
					$rss_url = get_the_author_meta( 'rss_url' );
					if ( $rss_url && $rss_url != '' ) {
						echo '<li class="rss"><a href="' . esc_url($rss_url) . '"><span class="fa-stack fa-lg">
<i class="fa fa-square-o fa-stack-2x"></i>
<i class="fa fa-rss fa-stack-1x"></i>
</span></a></li>';
					}
					
					$google_profile = get_the_author_meta( 'google_profile' );
					if ( $google_profile && $google_profile != '' ) {
						echo '<li class="google"><a href="' . esc_url($google_profile) . '" rel="author"><span class="fa-stack fa-lg">
<i class="fa fa-square-o fa-stack-2x"></i>
<i class="fa fa-google-plus fa-stack-1x"></i>
</span></a></li>';
					}
					
					$twitter_profile = get_the_author_meta( 'twitter_profile' );
					if ( $twitter_profile && $twitter_profile != '' ) {
						echo '<li class="twitter"><a href="' . esc_url($twitter_profile) . '"><span class="fa-stack fa-lg">
<i class="fa fa-square-o fa-stack-2x"></i>
<i class="fa fa-twitter fa-stack-1x"></i>
</span></a></li>';
					}
					
					$facebook_profile = get_the_author_meta( 'facebook_profile' );
					if ( $facebook_profile && $facebook_profile != '' ) {
						echo '<li class="facebook"><a href="' . esc_url($facebook_profile) . '"><span class="fa-stack fa-lg">
<i class="fa fa-square-o fa-stack-2x"></i>
<i class="fa fa-facebook fa-stack-1x"></i>
</span></a></li>';
					}
					
					$linkedin_profile = get_the_author_meta( 'linkedin_profile' );
					if ( $linkedin_profile && $linkedin_profile != '' ) {
						echo '<li class="linkedin"><a href="' . esc_url($linkedin_profile) . '"><span class="fa-stack fa-lg">
<i class="fa fa-square-o fa-stack-2x"></i>
<i class="fa fa-linkedin fa-stack-1x"></i>
</span></a></li>';
					}
				?>
			</ul>
		</div>
	</div>
	<!--END .author-bio-->