Because you have nothing done, I'll give you what I have here .. maybe not 100% what you want, but it will give you a way.
A basic idea, you may have to readjust the image.
//Cria um novo documento
iTextSharp.text.Document Doc = new iTextSharp.text.Document(PageSize.LETTER, 20, 20, 20, 20);
//Salve o documento
string PDFOutput = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Output.pdf");
PdfWriter writer = PdfWriter.GetInstance(Doc, new FileStream(PDFOutput, FileMode.Create, FileAccess.Write, FileShare.Read));
//Abra o PDf
Doc.Open();
string Folder = "C:\Images";
foreach (string F in System.IO.Directory.GetFiles(Folder, "*.jpg")) {
// Inserir uma pagina
Doc.NewPage();
//Adicionar uma Imagem
Doc.Add(new iTextSharp.text.Jpeg(new Uri(new FileInfo(F).FullName)));
}
//Fechar pdf
Doc.Close();