It's not possible in QGIS 2.0.
Status Oct 2013 http://osgeo-org.1560.x6.nabble.com/is-it-possible-in-QGIS-to-export-or-save-a-map-in-the-GeoPDF-format-td5081041.html#a5081059
Export to GeoPDF is not yet supported by QGIS. The new features in QGIS are user/developer/customer driven. If you want a new feature you can either develop it yourself, ask a developer you know or hire a developer.
OGR has support for GeoPDF. So a potential developer of this feature could probably make use of OGR.
Some more details from 2012 http://osgeo-org.1560.x6.nabble.com/GeoPDF-td5017192.html
The situation with GeoPDF is a bit similar to DXF - which basically
means that although ogr supports it it will be a LOT of work to support
it, because of the following:
- QGIS needs to support OGR feature styling first - needs to
automatically convert QGIS symbology to OGR feature styling. The problem
here is, that QGIS has a richer symbology feature set than OGR and it
would only work for simpler symbology anyway.
- QGIS needs to support the export of several QGIS layers into one OGR
- SVG symbols need to be converted into symbols that OGR can digest -
or we have enhance OGR to support SVG to xx conversion.
- while exporting you probably also want to take into account a certain
export map scale (e.g. exporting for scale of 1:1000) and QGIS would
have to read all symbology and label rules for that certain map scale to
apply them - even if GeoPDF and DXF are in real-world coordinates.
All of these mean probably several hundred hours of work.
But then improved DXF support has already been announced for 2.2. Maybe that means that supporting GeoPDF can now be done with less effort.