[Plugin: Reaction Buttons] Display thumbnail in most clicked widget

I have the widget displaying the title of the posts, but I also want the thumbnails (featured image) to be displayed. Can you tell me how/where to put that code? I have this code on my regular posts to show the thumbnail

<?php if ( has_post_thumbnail()) : ?>
” title=”<?php the_title_attribute(); ?>” >
<?php the_post_thumbnail( ‘category-thumb’ ); ?>

Thanks for your help!

https://www.ads-software.com/extend/plugins/reaction-buttons/