Help for a newbie please

Hi there.
I have added this below code to the header file in twenty eleven (child). But what I cant seem to figure out is how to set it for a certain page. Which is page ID 7.

I want to say IF the function exists then use it on page 7 only.

Im really really stuck on this one. Help would be greatly appreciated.

<?php if ( function_exists( ‘meteor_slideshow’ ) ) { meteor_slideshow( “touch”, “” ); } ?>

thank you.