How take a SkiaSharp SKData and write out a pdf?

Our app uses SkiaSharp and Xamarin Forms to create sketches. We can take a completed sketch and write it out as a jpg.
SKData skData = surface.Snapshot().Encode(); using (Stream stream = File.Open(fileout, FileMode.OpenOrCreate, System.IO.FileAccess.Write, FileShare.ReadWrite)) { skData.SaveTo(stream); }

How do I write it out as a pdf?

One step is to create an SKDocument like this:
SKDocument skDocument = SKDocument.CreatePdf(SKWStream, dpi);
How do I turn the SKData into an SKWStream?

Thanks for having a look at this.