WordPress at a glance
filter is not described

the_permalink_rss filter-hook . WP 2.3.0

Filters the permalink to the post for use in feeds.

Usage

add_filter( 'the_permalink_rss', 'filter_function_name_8330' );
function filter_function_name_8330( $post_permalink ){
	// filter...

	return $post_permalink;
}
$post_permalink(string)
The current post permalink.

Where the hook is called

the_permalink_rss()
wp-includes/feed.php 245
echo esc_url( apply_filters( 'the_permalink_rss', get_permalink() ) );

Where the hook is used (in WP core)

Does not used.