How to change font of the pdf content when converting from HTML to PDF

 Public Shared Function ExportHTM()
    Dim sbytes As [Byte]()
        Using mstream = New MemoryStream()
            Using PDF = New Document(iTextSharp.text.PageSize.A4, 5, 5, 15, 5)
                Using writer = PdfWriter.GetInstance( PDF, mstream )
                   PDF.Open()
                    Using StringWriter= New StringWriter()
                        Using HtmlTextWriter = New HtmlTextWriter(StringWriter)
              'How to apply  font and styles to pdfcontent' -- PDF content is a string and it contains html content
                            Using StringReader = New StringReader(pdfcontent)
                                Using htmlparser = New HTMLWorker( PDF)
                                    htmlparser.Parse(StringReader)
                                End Using
                            End Using
                        End Using
                    End Using
                    PDF.Close()
                End Using
            End Using
            sbytes = mstream.ToArray()
           mstream.Close()
        End Using
END function