Firstly, not all peasants were private serfs:
"By the mid-19th century, the peasants composed a majority of the population, and according to the census of 1857 the number of private serfs was 23.1 million out of 62.5 million Russians, 37.7% of the population.
The exact numbers, according to official data, were: entire population 60,909,309; peasantry of all classes 49,486,665; state peasants 23,138,191; peasants on the lands of proprietors 23,022,390; peasants of the appanages and other departments 3,326,084. State peasants were considered personally free, but their freedom of movement was restricted"
Secondly, private serfs could be hired out by their owners - to specific employer, or just by giving permission to find the job themselves, and pay to owner agreed amount of money. In Russian it called "Оброк":
Hired-out serfs were not free, but they could buy themselves out if they accumulated enough money. Serfs working land could do it as well, if they were allowed to keep significant part of the crop.
Don’t know your goal (article, educational project, or just curiosity), but keep in mind following:
Because not all peasants were serfs, “November 1818 request for passports identifies a third of the employees as peasants” actually does not tell how many serfs were in fact employed by Russian-American Company. State peasants might also need passports to live outside the place they were permanently assigned.
The Оброк picture is more complicated than serfs live and work outside their master’s estates. There were two major forms how serfs serviced their masters: working directly for them (“барщина”), or making scheduled (usually annual) payment in money and/or goods. The later form called “оброк”, and serfs could perform it either by working assigned to them portion of master’s land, paying to masters “оброк” and keeping rest for themselves, or - with masters permission - work and live somewhere else.
In general, it was possible (but not common) for serfs to live and work not at the masters estate, and not to pay “оброк”. Hey could be send by masters to get education or training in some occupation masters would benefit in a future. Or, as rare exception, masters, for humanitarian reasons, could let really talented serfs earn money and buy their freedom (manumission was not encouraged by authority and society).
It was related question few years ago, and the first answer ( by Darek Wędrychowski) provided good information and source in English (my knowledge of this subject is from Russian sources, and I did not research, just general literature):
How compare the rights and conditions of the American slaves to those of Russian serfs?