This is the 7799th most frequent Russian word.
искитимскому
The word "искитимскому" means "related to Iskitim" (a town in Russia) in the dative case.
Here, the word "искитимскому" is in the dative case, modifying "главе администрации" to indicate to whom the letter is sent.
Мы отправили письмо искитимскому главе администрации.
We sent a letter to the Iskitim administration head.
In this sentence, "искитимскому" is also dative, but it modifies "району" to specify the recipient of the funds.
Искитимскому району выделили дополнительные средства.
Additional funds were allocated to the Iskitim district.
Here, "искитимским" is in the instrumental case and describes "заводом," indicating a relationship of cooperation.