Adding an image to a PDF using iTextSharp and scale it properly

here's my code. It correctly adds the pictures I want and everything works except that the images are using their native resolution, so if the image is big it's being cropped to fit the page.

Is there some way to have the picture use like a Zoom feature to stretch to fit, but also maintain the aspect ratio? There has to be something I'm missing there. :P

Here's a picture to illustrate the problem:

using System;
using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.Drawing;
using System.Collections.Generic;

namespace WinformsPlayground
{
    public class PDFWrapper
    {
        public void CreatePDF(List<System.Drawing.Image> images)
        {
            if (images.Count >= 1)
            {
                Document document = new Document(PageSize.LETTER);
                try
                {

                    // step 2:
                    // we create a writer that listens to the document
                    // and directs a PDF-stream to a file

                    PdfWriter.GetInstance(document, new FileStream("Chap0101.pdf", FileMode.Create));

                    // step 3: we open the document
                    document.Open();

                    foreach (var image in images)
                    {
                        iTextSharp.text.Image pic = iTextSharp.text.Image.GetInstance(image, System.Drawing.Imaging.ImageFormat.Jpeg);
                        document.Add(pic);
                        document.NewPage();
                    }
                }
                catch (DocumentException de)
                {
                    Console.Error.WriteLine(de.Message);
                }
                catch (IOException ioe)
                {
                    Console.Error.WriteLine(ioe.Message);
                }

                // step 5: we close the document
                document.Close();