I'm not familiar with Signlab but if it allows you to create multiple pages in a single file, then you should be able to just print through the standard windows driver and choose, "Print as PDF" instead of a printer. This will create a multi page PDF. If the software doesn't allow you to do those things, the only other way I know of is to save each page as a separate job and then use Adobe Reader Professional to combine them. Maybe there is an open source alternative out there too.