Hi, All.
I think, opinion of Qrt.S is right . It is Kamenets-Podolsk. But the Kamenets-Podolsk isn't "a small village by the river of Dnepr south west of Kiev")))) It is an ancient town with nice history.
Unfortunately, in the
P-L's book there is an error (or a typing error). The unique example of townmark is wrongly dated by 18 century. It is wrong. It is mark of 19th century.
Kamenets-Podolsk became a part of the Russian Empire after
1793 only. When Austria, Prussia and Russia have once again divided
Poland.
"Townmark" for “Podolskaya Probirnaya Palatka” (Podolsk assay office) began to be used only from the nineteenth century. It looked like as at other new attached territories, such as Minsk and Warsaw. "Townmark" is the Russian Empire's two-headed Eagle.
For example:

Therefore: Kamenets-Podolsk, assaymaster
ИЛЬИÐ
ПЕТРЕФИМОВИЧ (Ilyin Petr Efimovich).
Makermark is difficult to determine under other marks.
For an example:

Best Reg..