leecrockett on "[Theme: Customizr] Feature images in posts"

I've come across this code for automatically including a feature image on every page if it exists

add_filter( 'tc_content_headings_separator', 'my_extra_image' );
function my_extra_image() {
	if ( has_post_thumbnail() ) { // check if the post has a featured image assigned to it.
  		echo '<hr class="featurette-divider">';
  		echo the_post_thumbnail();
	}
}

Which does make the image appear, but the full size image. I'd like it to be the same rounded image sized properly like on the blog list, which is a div floated right. No idea how.