Believe it to be again Johannes Feddema, registered in Leeuwarden 1780-1825

I.F in rectangle under crown
https://www.925-1000.com/forum/viewtopi ... 64#p230664
Crowned O, duty free mark of 1807
Crowned V in shield
Crowned V for large items; duty mark for foreign and other untaxed objects used 1814-1893. This duty mark does not give any guarantee of a precious metal standard of fineness. This mark has been used on metal with a 250 minimum silver content as a duty mark. This mark was destined for all imported, unmarked and invalid marked objects of foreign, national and unknown origin. Upon the invalidation of the hallmarks of Louis Napoleon's kingdom of Holland and those of the French Empire in 1816, this mark also has been used as a tax free census mark.
The mark on the belt hook

Looks like a hammer.
Perhaps a blacksmith's hammer for Jippe Klases Smedema, registered in the Frisian city of Dokkum, 1781-1832, born 1750, died 1832
Peter.