Specifically methylates the guanine in position 966 of 16S rRNA in the assembled 30S particle. guanosine(966) in 16S rRNA + S-adenosyl-L-methionine = H(+) + N(2)-methylguanosine(966) in 16S rRNA + S-adenosyl-L-homocysteine Belongs to the methyltransferase superfamily. RsmD family.