[Mike Turner]

I have had the same issue exporting under the “QuickTime Movie” choice, but try this instead:
Go File>Export>Using Quicktime Conversion.
Choose “QuickTime Movie” from the drop down and then hit the options button.
Under the “Video” section hit the “Size” button. There is a drop down for “Dimensions” that gives you plenty of choices.
Go to the bottom half and pick one depending on your edit format, SD, HD, PAL, etc.
You can even enter in customized dimensions by choosing “Custom” and entering the numbers yourself.
Good luck,
Mike

[Mike Turner]

I actually tried to do something similar by exporting one of my clips as 853×480 and dropping it in a 4:3 timeline but I still had to scale up 13%. Thanks for your suggestion, maybe I’ll give Motion a try.
Mike