Coding Question – "The Excerpt"

I have a custom RSS feed that is showing the whole content of my posts. I want to change it to showing only the excerpt… the relavent piece of code looks like this:

‘<description><?php echo ‘<![CDATA[‘.apply_filters(‘the_content’, $post->post_content).’

ID).'”>’.get_the_title($post->ID).’‘.’]]>’; ?></description>’

I’m assuming I just need to change “post_conent” to something like “the_excerpt” but no combination of words seems to work.

Does anyone know the right code?

Thanks!