Hi there,
Apologies for the delayed reply. I think this is because by default the show read more is set to none, and the search results doesn’t have it set. So what you want to do is edit /includes/sf-content-display/sf-post-formats.php line 197 to:
function sf_get_post_item($postID, $blog_type, $show_title = "yes", $show_excerpt = "yes", $show_details = "yes", $excerpt_length = "20", $content_output = "excerpt", $show_read_more = "yes") {
Hope that helps.
– Ed