[Marck-antoine Simoneau]

Hi Keshet,
I found by myself this rendering setting that can render video vertically.
Go to File -> Render As
Then, open MainConcept AVC/AAC (*.mp4;*.avc) and select Internet HD 1080p
Scroll down and click on Customize Template…
In the Frame size: select (Custom frame size) and write your Width: 1080 and Height: 1920 or any values you need.

Now it should work, at least it did for me, I’m using Sony Vegas Pro 13.0