jf. help kan man ikke gøre det i bare en præsentation...
Use portrait and landscape orientation in the same presentation
By default, slide layouts are set up for landscape orientation.
Move the slides you want to be in portrait orientation to a new presentation file.
How? (link)
On the Slides tab in normal view, select the slides you want to change.
On the Edit menu, click Cut.
Open a new blank presentation.
On the Edit menu, click Paste.
Change the orientation of the slides in the presentation.
How? (link)
On the File menu, click Page Setup, and click Portrait under Orientation for Slides.
Save the new presentation.
Create a link from your original presentation to the new presentation.
How? (link)
Select the text or object you want to be the link to the new presentation.
On the Slide Show menu, click Action Settings.
Click Hyperlink to, and then click Other PowerPoint Presentation in the list.
Browse to the new presentation and click OK.
Create a link from your new presentation back to the original presentation.
How? (link)
Select the text or object you want to click on to return to the original presentation.
On the Slide Show menu, click Action Settings.
Click Hyperlink to, and then click Other PowerPoint Presentation in the list.
Browse to the original presentation and click OK.
In the Slide title list, select the slide title that you want to link to in the original presentation, and click OK.
Save both presentation files.
Note You will always need both presentation files to present this slide show, and the files must be kept in the same directories that you browsed to when you set up the links.