You could try:
1. Disabling the author output in the settings.
2. Adding this function:
add_filter( 'wpsp_date_output', 'tu_custom_wpsp_date_output' );
function tu_custom_wpsp_date_output( $output ) {
$author = sprintf(
'<span class="wp-show-posts-byline wp-show-posts-meta">
<span class="wp-show-posts-author vcard" itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author">
<a class="url fn n" href="%1$s" title="%2$s" rel="author" itemprop="url">
<span class="author-name" itemprop="name">%3$s</span>
</a>
</span>
</span>',
esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
esc_attr( sprintf( __( 'View all posts by %s', 'wp-show-posts' ), get_the_author() ) ),
esc_html( get_the_author() )
);
return $output . ' by ' . $author;
}
Let me know 🙂