[scribus] Flattening layers?

[Willem (Pim) Borman]

I use Scribus 1.3.3.11 in Ubuntu Linux (Gutsy Gibbon) on a computer with a  AMD Athlon 64 processor.
I composed my first newsletter in Scribus following the examples in the tutorial, using two layers for the constant and variable contents.

When I exported the final product (8 pages) to PDF I received error warnings. They referred to missing images and such, none of which seemed to be the case. I chose to ignore the warning and the document exported correctly to pdf format. I made sure the images were being reduced to 72 dpi and the output intended for Web/Screen purposes.
The file size of the pdf document was about 2.8 MB which seemed to be excessive. I thought it might help to flatten the original document to a single layer before exporting to pdf. That might also resolve the error warnings.
QUESTION: How do you flatten multiple layers to a single one? I can't find any ways to do that. If it can't be done I'll lay out the next newsletter issue in a single layer and see if that helps.
Willem Borman (wilborm at yahoo.com)