I’ve been looking all over for the working script that ensures in various browsers that the facebook canvas size will be set (even when using some slow loading javascript code). Just set this in your facebook APP page and it should work!

<div id="fb-root"></div>
<script type="text/javascript">
    window.fbAsyncInit = function () {
        FB.init({ appId: 'YOUR APP ID', status: true, cookie: true, xfbml: true });
        FB.Canvas.setSize({ height: 890 });
    };
    (function () {
        var e = document.createElement('script');
        e.type = 'text/javascript';
        e.src = document.location.protocol +
            '//connect.facebook.net/en_US/all.js';
        e.async = true;
        document.getElementById('fb-root').appendChild(e);
    } ());
</script>