نقل قول: This is my guide for show the button
Please open file /plugins/content/bt_socialshare/bt_socialshare.php
Find this line
$k2 = substr_count($context, 'com_k2');
Add new line below it

if(!$k2){
$this->html .= 'RSS';
}

You will see a RSS link at lead of buttons.
You can change position of button by bring it to positions under code that get other buttons.

You also need to style the button with class "button-rss"