Hi,
My Boxster had the exact same appearance for the oil leak. After tear down, I believe the leak was coming from the IMS flange. It was the old single o-ring type seal. The IMSB was totally fine (even though I still replaced it). I replaced the RMS, but it too looked fine.
See pics here:
Oil Leak - Pulling Trans to change RMS, IMS, Clutch, etc