สอบถามการใช้ iTextSharp หน่อยครับ ในกรณี htmlworker ครับ

//Dummy data for Invoice (Bill).
            string companyName = "ASPSnippets";
            int orderNo = 2303;
            DataTable dt = new DataTable();
            dt.Columns.AddRange(new DataColumn[5] {
                            new DataColumn("ProductId", typeof(string)),
                            new DataColumn("Product", typeof(string)),
                            new DataColumn("Price", typeof(int)),
                            new DataColumn("Quantity", typeof(int)),
                            new DataColumn("Total", typeof(int))});
            dt.Rows.Add(101, "Sun Glasses", 200, 5, 1000);
            dt.Rows.Add(102, "Jeans", 400, 2, 800);
            dt.Rows.Add(103, "Trousers", 300, 3, 900);
            dt.Rows.Add(104, "Shirts", 550, 2, 1100);

            using (StringWriter sw = new StringWriter())
            {
                using (HtmlTextWriter hw = new HtmlTextWriter(sw))
                {
                    StringBuilder sb = new StringBuilder();

                    //Generate Invoice (Bill) Header.
                    sb.Append("<table width='100%' cellspacing='0' cellpadding='2'>");
                    sb.Append("<tr><td align='Left' style='background-color: #18B5F0'><b>ทดสอบ หนึ่ง</b></td><td align='Right' style='background-color: #18B5F0'><b>Order Sheet</b></td></tr>");
                    sb.Append("<tr><td colspan = '2'></td></tr>");
                    sb.Append("<tr><td><b>Order No: </b>");
                    sb.Append(orderNo);
                    sb.Append("</td><td align = 'right'><b>Date: </b>");
                    sb.Append(DateTime.Now);
                    sb.Append(" </td></tr>");
                    sb.Append("<tr><td colspan = '2'><b>Company Name: </b>");
                    sb.Append(companyName);
                    sb.Append("</td></tr>");
                    sb.Append("</table>");
                    sb.Append("<br />");
                    //Generate Invoice (Bill) Items Grid.
                    sb.Append("<table border = '1'>");
                    sb.Append("<tr>");
                    foreach (DataColumn column in dt.Columns)
                    {
                        sb.Append("<th style = 'background-color: #D20B0C;color:#ffffff'>");
                        sb.Append(column.ColumnName);
                        sb.Append("</th>");
                    }
                    sb.Append("</tr>");
                    foreach (DataRow row in dt.Rows)
                    {
                        sb.Append("<tr>");
                        foreach (DataColumn column in dt.Columns)
                        {
                            sb.Append("<td>");
                            sb.Append(row[column]);
                            sb.Append("</td>");
                        }
                        sb.Append("</tr>");
                    }
                    sb.Append("<tr><td align = 'right' colspan = '");
                    sb.Append(dt.Columns.Count - 1);
                    sb.Append("'>Total</td>");
                    sb.Append("<td>");
                    sb.Append(dt.Compute("sum(Total)", ""));
                    sb.Append("</td>");
                    sb.Append("</tr></table>");

                    //Export HTML String as PDF.
                    StringReader sr = new StringReader(sb.ToString());                  
                    Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);
                    HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
                    PdfWriter writer = PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
                    pdfDoc.Open();
                    BaseFont bffont = BaseFont.CreateFont(@"C:\Users\User\Documents\Visual Studio 2012\Projects\MemberChart\MemberChart\Service\ANGSA.TTF", BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);
                    Font fontozel = new Font(bffont, 12);
                    //pdfDoc.Add(new Paragraph("ถ้าใช้อันนี้ผมทำให้มันเป็นภาษาไทยได้", fontozel)); 
                    htmlparser.Parse(sr);  //แต่ถ้าใช้ html มันอ่านค่าภาษาไทยไม่ได้ครับ
                    
                    pdfDoc.Close();
                    Response.ContentType = "application/pdf";
                    Response.AddHeader("content-disposition", "attachment;filename=Invoice_" + orderNo + ".pdf");
                    Response.Cache.SetCacheability(HttpCacheability.NoCache);
                    Response.Write(pdfDoc);
                    Response.End();
                }
            }