It is quite easy to export a rendered RadChart to PDF format. You would use the RadChart.Save() method to save your chart as an image or to a memory stream. Then, you can use any third party converter that you prefer to output the image as PDF.
Another option is to embed RadChart within a RadGrid “GridTemplateColumn” and then to take advantage of the RadGrid Export Functionality to simplify things. This is covered in the code library project: Exporting RadChart to PDF
I hope this helps!