Unity Ads Service: How do i resize ads?

I use [Unity Ads][1] to create ads for my game. I can create ads using `Advertisement.Show();`, but this creates a fullscreen ad. ![alt text][2] How can I resize the ad to take up only a part of the screen: half left, half top, etc. [1]: https://docs.unity3d.com/Manual/UnityAds.html "Unity Ads" [2]: /storage/temp/85039-untitled.png