Force the Read More link to show on manual excerpts when the Genesis --> Theme settings is set to show post excerpts.

gistfile1.php

<?php

// Add Read More button to blog page and archives
add_filter( 'excerpt_more', 'wsm_add_excerpt_more' );
add_filter( 'get_the_content_more_link', 'wsm_add_excerpt_more' );
add_filter( 'the_content_more_link', 'wsm_add_excerpt_more' );
function wsm_add_excerpt_more( $more ) {
    return '<span class="more-link"><a href="' . get_permalink() . '" rel="nofollow">Read More</a></span>';
}

// Force Read more on manual excerpts
add_filter( 'get_the_excerpt', 'wsm_add_manual_excerpt_more' );
function wsm_add_manual_excerpt_more( $more ) {
    global $post;
	// Check for manual excerpts & display if found
	if ( !empty( $post->post_excerpt ) ) {
		return $post->post_excerpt . wsm_add_excerpt_more( $more );
	}
	// Just keep rollin' if there are no manual excerpts
	else {
		return $more;
	}
}