You can do it by creating a hook for post_row_actions
filter. If your CPT is hierarchical post type use page_row_actions
filter.
add_filter( 'post_row_actions', 'wpse8170_row_actions', 10, 2 );
function wpse8170_row_actions( $actions, WP_Post $post ) {
if ( $post->post_type != 'my-custom-post-type' ) {
return $actions;
}
$actions['wpse8170-pdf'] = '<a href="http://your/url/here">PDF</a>';
return $actions;
}