Change date format "Posted by"

I found out the solution myself, in case anybody is interested:)

I just added this filter to functions.php and added {la_date} to the template:

add_filter('sf_post', 'sf_replace_custom_values', 1, 10);
function sf_replace_custom_values($post) {
$format = 'd/m/Y';
$pfx_date = get_the_date( $format, $post->ID );
$post->la_date = $pfx_date;
return $post;
}

Well no, because I want to display it in a custom way, different from the date_format used elsewhere in the blog.