Hi J.S, welcome to the forum.
Dutch silver and made in the city of Utrecht, province of Utrecht.
The various variations of the Utrecht townmark.
Utrecht town mark struck twice to indicate 1st standard silver. (town mark + province mark of Utrecht) 934/1000 fineness.
The crowned O is a later added taxfree mark.
The maker's mark CS for; Cornelis J. van Straatsburg, registered in Utrecht during 1748-1803. However it comes with a warning that this mark can also be encountered as a falsification. The year letter D for 1763 or 1787. My impression, the combination of date letter and townmark are for 1787. Below the maker's mark CS for Cornelis Johannus van Straatsburg:
Redeem and tax mark of 1795;
Utrecht's hat of Liberty, placed on a spear planted in the ground.
Please show us some enhanced, clear images of the marks, daylight, no flashlight. The weight of the salver and dimensions also, thanks.