XVIII Dutch? French (?) silver beacker - SOS marks

Hello!
I would like your opinion on this silver beacker from my collection.
It looks like XVIII century and has a nice patina. I am not able to identify the marks and they look unusual to me.
The marks are on the bottom of the piece and also on the foot (see images).
Dutch? French? what could it be?
Please let me know what you think about it. Thanks!

Edited by Moderator to show images…


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No clues anyone?