Rear main seal vs oil pan gasket? N52 128i

[shockpoint]

Hello!

Is anyone able to tell me whether the following is more likely to be a rear main seal or a oil pan gasket job?
On inspection the fluid looked more like fresh motor oil than transmission fluid.
I’ve attached two pictures.
I noticed an increased loss of motor oil, by the end of my usual service period i had oil at the lower notch of the electronic oil level sensor! Checking all other areas there were no leaks.
Thank you!

[blue135]

You could clean it and monitor it to find source? Time and effort, but you would have a sense of what to attack.