Low oil, possible damage?
 

Was putting my Boxster away for winter , my 20 year old son wanted to help.
I had him do pretty much everything as I watched except one item.
Filling the oil.I told him to add 7 3/4 litres which I know he's more than capable of doing but he herd me wrong and only added 7 litres.After filling, my wife jumped in before I could look at oil level (this is an 06 with electronic level readout) but I figured it was fine and I would check when she returned.So off she went for a 20 minute highway ride.
When she got back I checked to oil after it cooled down abit so it would read properly and the oil level readout was flashing below minimum.Wow!
I immediately added 1 quart which raised it to approx 3/4 setting were I typically keep it as to not overfill.Could I have done damage ,there was a very light rattle coming from engine .I have not driven it since.Any advise welcome.I did ask my wife and she never
reved much over 4500 rpm.

I think you’ll be fine. The car would generally let you know with flashing lights if you had really f’d up. ;)

Agree. You were down less than a quart, and not for an extended time or under great stress.