this.ScalesPageToFit = true; has no effect

Hello,

I'm trying to implement a custom view renderer for my WebView and I can't figure out how to get a large webpage to automatically scale to fit the viewport.

using System;
using Xamarin.Forms.Platform.iOS;
using UIKit;
using Xamarin.Forms;
using ButtonCode;
using ButtonCode.iOS;
using Foundation;

[assembly: ExportRenderer(typeof(CustomWebView), typeof(CustomWebViewRenderer))]
namespace ButtonCode.iOS
{
    public partial class CustomWebViewRenderer : WebViewRenderer
    {
        protected override void OnElementChanged(VisualElementChangedEventArgs e)
        {

            base.OnElementChanged(e);

            if (e.OldElement==null)
            {
                this.ScalesPageToFit = true;
                //this.ScrollView.ScrollEnabled = false;
            }
        }
    }
}

The code executes without error or warning. To be sure that the web view object is being accessed I tried another property, this.ScrollView.ScrollEnabled, and setting it to false had the expected effect.