The Boars head or the 1831 duty mark, this mark is of two sizes. It did not give any guarantee on precious metal content. It has been used as a duty mark on metal with a gold or silver content of 250 minimum. This mark was destined for all imported, unmarked and invalid marked objects of foreign, national and unknown origin. The big sized Boars head used 1831-1855 and the small Boars head used 1831-1893
One has the town mark of Rotterdam; 4 lion's passant facing left in four quarters above vertical bar in a crowned shield viewtopic.php?p=97785#p97785
Year letter C for 1785
The maker's mark appears to me VL conjoined/monogram in oval for; Hendrik van Laar, registered in Rotterdam 1783-1807, born 1765
P.K P.K could be for; Peter Johan Nicolaas Kruseman, registered in Leeuwarden 1807-1819. https://de-paula-lopes.nl/lidworden/01c ... index.html
Or perhaps pseudo marks, see K.A. Citroen Valse Zilvermerken in Nederland; P.K in rectangle pseudo maker's mark # 285 and two stars in rectangle pseudo maker's mark # 475
Peter.
source; N.I. Schadee, Zilverschatten, drie eeuwen Rotterdams zilver. Elias Voet, Merken van Friesche goud-en zilversmeden