random redirect with random refer

i can random redirect with this code:

<?php
$addresses = [
        "http://site1.com",
        "http://site2.com",
        "http://site3.com",     
];
$size = count($addresses);
$randomIndex = rand(0, $size - 1);
$randomUrl = $addresses[$randomIndex];
header('Location: ' . $randomUrl, true, 303);

i want to make random refer for random redirects. please help me . i'm beginner.