I can't for the life of me remember which character it was that had this primitive in it. But I swear there was a character that had the primitives 'bamboo' and this in it and possibly another primitive but not sure. Can anyone remember? Tell me I'm not dreaming this up.

=SSS

Do you mean this? 箋

It's used in writing paper and prescription 処方箋

便箋 (stationary) is the only other semi-common word using that kanji, I think.

In older Japanese it was used to mean "commentary" but I don't think that meaning survives into modern use.

YES!!!! that's the character. Great I can sleep now! I was confused because the old form of 'coin' found in one of the unicodes said this primitive was the old form of 'float' but I was pretty sure it was in one of the kanji. I searched my whole RTK kanji poster but couldn't find it! Thanks guys ! you're so smart!!

Is it called "stationary" in the book? Because there's a difference between "stationary" and "stationery." Stationary is incorrect.

It's named correctly in the supplement pdf.

Yep, it's incorrectly "stationary", at least in the edition that's on Google Books (and in at least one RTK deck).

I don't even have RTK 1; I just didn't know how to spell the word.

Yeah, 戔 is a radical in traditional hanzi that simplifies to 戋. From there, you can add the extra stroke to make it "float". So probably any kanji that uses "float" could have an old form with 戔.