doc.Name = "FlowDoc";
doc.PageWidth = 210;
doc.PagePadding = new Thickness(3, 5, 2, 4);
// Create IDocumentPaginatorSource from FlowDocument
IDocumentPaginatorSource idpSource = doc;
// Call PrintDocument method to send document to printer
printDlg.PrintDocument(idpSource.DocumentPaginator, "Receipt Printing.");