I made LinkedIn support for myself, hopefully the author can place it upstream.
// LinkedIn Button
if(get_option('ss_linkedin','1')){
$simplesocialcontent .= '<a onclick="return simplesocial(this,570,520)" class=simplesocial title="LinkedIn" style="background:url('.$simplesocial_dir.'linkedin.png)"
href="https://www.linkedin.com/shareArticle?mini=true&url='.$simplesocial_enclink.'&title='.$simplesocial_title.'"></a>';
}
Add this, plus a ‘linkedin’ to the $simple_social_icons=array(), ca. line 120.
Icons are from here.
