Yes I have, and unfortunately, my tv is not the newest, and the only picture adjustments available are color related. I've also gone through the roku menu and tried changing the resolution down to 720p and it didn't help.
There may not be anything you can do. I've seen a cheap Chinese TV that won't allow any picture adjustments and when I connect a Roku the edges of the picture are cut off, but it's not too bad. Does the TV have more than one HDMI input you could try? Unfortunately Rokus don't have any kind of picture size adjustments.