I've checked the application, but the PDF option doesn't exist which means you have to do this in another way. Access the following link to download CutePDF Writer: http://www.cutepdf.com/Products/CutePDF/writer.asp
Install it and make sure you are connected to the Internet since it needs to download some support libraries. Once the app is installed, open the XLS file and go to File > Print Setup. Choose the CutePDF Writer from the list and continue with the print procedure. You will be prompted to save the PDF file. Type a name and that's it.