Can I add my own icon?

Hi donpro,
The plugin is only for social icons. But you have 2 hooks in the code to add anything before or after the icons.
the hooks are sfmsb_widget_before_links and sfmsb_widget_after_links

For example you can add this in your functions file:

add_action('sfmsb_widget_after_links', 'display_my_icon');

function display_my_icon(){
  echo '<a href="https://url_to_my_page">here my icon</a>';
}