PDF format is essential to Scribus. Although Scribus can produce perfectly good content for the web, it is designed to produced high-quality printed material, and PDF is the standard format at most printing houses, aside from the occasional one that still prefers Postscript. At the same time, among its wealth of PDF options, Scribus also includes several options for various online purposes as well.
The PDF options are available from File -> Export -> Save as PDF. At the top of the PDF window, you can set the path and name for the PDF files being created, and also opt to produce one file per page, which is useful if you are making separations. These files will be named according to the name you set, so that if you enter the name project.pdf, the files' names will begin with project1.pdf and project2.pdf.
Below these basic options are seven tabs of options. From left to right, they are:
This tab contains some of the options you can see in standard printing dialogs, such as the range of pages to print. You can also opt to clip to printer margins if you are sure that your design has not over-ridden them, producing a slightly small page than otherwise. You can even rotate pages, although in the most common circumstances where this option would be useful -- changing between landscape and portrait page orientation -- you are probably better off working within Scribus than from the PDF export dialog.
In addition, the General tab also includes options unique to quality printing PDF files. To start with, you can set the version of PDF that you want in the output. Scribus supports PDF versions 1.3, 1.4, and 1.5, as well as X-3 if color management is enabled. Technically, the lower the version, the more widely compatible your output will be, but since Scribus' support is well-behind Adobe's versions, in practice compatibility will not be an issue.
However, you will need at least 1.4 if you are producing transparencies. Another limitation is that you will have no security options available if you are using X-3, and can only embed fonts -- which means that some fonts may be unavailable for use (see below).
For PDFs that will be printed to paper, you may also want to set the side on which output will be bound, although that will almost always be the default left margin for English texts.
Other check boxes on the tab give you the option of including navigation aids such as thumbnails, PDF articles, and Bookmarks. If you choose PDF version 1.5, you also have the option of including Scribus layers to create watermarks that are visible only when printing.
Should you want EPS graphics, you can also set their resolution in the PDF. For printing, you want at least the default of 300dpi, although you can go higher if the graphics themselves support it. Conversely, for online use, you can go as low as 72dpi, and keep the output from being unnecessarily large.
At the bottom of the tab, you can also adjust the compression for text and any vector graphic formats. Many printers prefer the Lossless-Zip option, with maximum compression. As with EPS graphics, you can also set the maximum image resolution.
Normally, PDF files embed only a sub-set of characters to save space. However, if you are willing to trade off file size, you can embed the complete font, which makes rendering and printing more reliable, especially if any difficulties arise.
On the Font tab, you can choose which fonts to embed. Usually, the font most often used for the body of the text is the first you will want to embed. In some cases, the limitations of the metrics contained in the font files will mean that only the outlines of fonts can be embedded -- a sort of second best option that is still better than nothing.