google conversion code

User needs it in his footer so I think you should use conditional page logic. Something like:

If ( is_single(postID)) { //insert tracking code  }

You can also use the post title or post slug, but id is the most reliable.

Old Answer

I would consider writing a shortcode. Add the following to your functions.php file. You can specify input parameters. In this case I specify id and target.

add_shortcode( 'signup', 'signup_shortcode' );

function signup_shortcode( $atts ) {
extract( shortcode_atts( array(
    'id' => '',
    'target' => '',
), $atts ) );

$HTML = 'hello world'.$id;

return $HTML;

}

Then call it in your post like so:

[signup id="1234" target="goog"]