To configure how a drawing page should be printed or exported to PDF use the PrintLayout property of the page. The following code demonstrates how to configure export of the whole drawing page to a single page of size A4:

NPagePrintLayout printLayout = drawingView.ActivePage.PrintLayout;
printLayout.PageSize = new NPaperSize(ENPaperKind.A4);
printLayout.PageColumns = 1;
printLayout.PageRows = 1;

Explore the other properties of the page's PrintLayout if you want to further customize the printing / export to PDF.

The following code shows a print dialog, which allows the user to print the active page:

NDrawingPrintExporter imageExporter = new NDrawingPrintExporter(drawingView.Content);
imageExporter.ShowDialog(drawingView.Content, true);

To skip the print preview and show the native print dialog directly, use the Print method of the print exporter:

NDrawingPrintExporter printExporter = new NDrawingPrintExporter(drawingView.Content)
printExporter.Print();