Get the code for berber yellow and ask your local PPG dealer to match it. Thats what I did for my paint . . . they have all of the colors by Porsche paint code on their computers.
Better yet, I would pull off a headlight cover and have your paint shop match it just in case your car isn't exactly beber yellow.
Just as a caution, colors don't look the same on computer as they do on the car, especially in the case of yellows and oranges. My summer yellow looks a little different on the car than it does on most online pictures.