Any thoughts about these hallmarks? Probably 18th century

[pitu]

Hello!
I have a problem with identifying these hallmarks on an old silver oklad. It looks to be made in 18th century, but I haven't found anything similar. I'd be grateful if you could share your opinion.

[Qrt.S]

Please read this http://www.925-1000.com/images.html

[pitu]

now pics should be ok

[Dad]

Hi

I think, these marks not of the Russian system. There can be the German system (loth). As in territories of the former Poland at the later years of 18 - the early 19 centuries. If, of course, it is the territory of the Russian Empire.