Hi robertM,
I assume your custom image field is using slug "image", and created by Types, please try modify 'wpcf-images' as 'wpcf-image'
More help: http://codex.wordpress.org/Function_Reference/get_post_meta
Are you going to set each image as different div's background-image?
Please try this:
$images = get_post_meta(get_the_ID(), 'wpcf-image');
$res = '';
foreach ($images as $index=>$image) {
$url = do_shortcode('[types field="image" url="true" size="medium" index=' . $index . ']');
$res .= '<div style="background-image:url( ' . $url . ');">div content for image index: ' . $index . '</div>';
}
echo $res;