As with EPS files, DPlot does not directly support output of the PDF format and the solution is very similar to the EPS problem. However, Windows isn't much help here and you'll need Adobe Acrobat or any other Adobe product that includes Acrobat Distiller or the Adobe PDF virtual printer driver. If you have Acrobat installed you should see Acrobat Distiller and/or Adobe PDF as one of the possible choices of printer in DPlot's Print dialog. Select it. You may also have an option of Acrobat PDFWriter. However, PDFWriter has problems with DPlot contour plots, while Distiller and Adobe PDF handle these plots perfectly.
Note: The Adobe printer drivers offer several methods for compressing bitmap images, with JPEG compression being the default. The JPEG method does compress the image very effectively, but the result is generally poor with DPlot-produced graphics. ZIP compression produces larger files but much better quality images.
If you do not have access to one of those Adobe products, there are several low-cost PDF virtual printer drivers available on the internet. The following vendors provide free trial versions of low-cost PDF printer drivers that have all been tested successfully with DPlot:
Pdf995 from Software995.
docuPrinter LT from Neevia Technology.
PDFcamp from veryPDF.
Win2PDF from Dane Prairie Systems.
If you have an active internet connection, you can see an example PDF file created with the Adobe PDF virtual printer driver distributed with Adobe Acrobat 7. Similar results are achieved with each of the products listed above.