Hi John, the image you use for a logo should be square, even if your actual logo is not. PNG format is correct, and it should also have a transparent background.
You can find a blank template and a pre-made iris360 patch at the below location - note though that as the size of the nadir hole is slightly different on every device, you may need to scale the image up or down to fit correctly, but please keep the height and width equal in size.