I put the cassette on the free hub this evening, but the outermost sprocket doesn't seem to seat in the splines.

This is a SRAM 970 9 speed. The cassette is all one piece except for the smallest (outermost) sprocket and the lock ring. The main body of the cassette slid on easily, and seemed to go onto the freehub as far as possible. But when I went to put the smallest sprocket on, it will just BARELY seat on the freehub splines, I mean barely - if I pushed down on it, it would seat enough to keep from spinning freely, but let up that pressure at all and it was if it didn't seat at all.

It is properly aligned with the splines.

I put the lockring on and just hand tightened it. That seemed to seat that cog more firmly, preventing it from spinning freely, but I'm not sure if it's really seated well. I did not torque it down, preferring to ask this esteemed forum if this seems normal. If so, I'll take the torque wrench and tighten the lockring.

Thanks again!