Wordpress RSS - Photos are not showing

I am having problems with showing photos in RSS in Wordpress. My theme is using custom field to display photos on website. I've seen the tutorials on how to grab the first image and display it in a post, and those on grabbing the post_thumbnail and using that in the RSS feed, but does anybody know how to grab image from custom field and use that in the RSS feed?

My theme is displaying images with following code on the archive page/homepage:

<?php if( get_post_meta($post->ID, "thumb", true) ): ?>
						<a href="<?php the_permalink() ?>" title="<?php the_title_attribute(); ?>"><img src="<?php $values = get_post_custom_values("thumb"); echo $values[0]; ?>" width="120" height="90" alt="<?php the_title(); ?>" /></a>
						<?php else: ?>
						<a href="<?php the_permalink() ?>" title="<?php the_title_attribute(); ?>"><img src="<?php bloginfo('stylesheet_directory'); ?>/images/noimage.gif" width="120" height="90" alt="<?php the_title(); ?>" /></a>
						<?php endif; ?>

PHP:

If anyone knows how to include photos from custom field to RSS please help me.
Thanks.