From what I gather of this thread on the OP Forums:
Clarity works like Health instead of Integrity in how it's tracked. Your Clarity track is equal to your Composure + Wits, and your first Touchstone goes at Composure + 1 from the left with extra's going to the right.
On the sheet, for space I guess, the Touchstone section is placed vertically. In this case up is left, and down is right.
So if you have Composure 3/Wits 3 and bought two extra Touchstones:
You have 6 Clarity boxes.
Ignore 7 - 11 on the Touchstone list.
Your first Touchstone goes on the 3 spot (Composure + 1 = 4, so it's the fourth slot down), the second on the 2 spot, and the third on the 1 spot.
If you take 4 severe Clarity damage, your first Touchstone becomes detached until you can heal the damage.
If you buy Composure 4, stop ignoring the 7 slot, but it remains blank. It just means it takes 5 severe Clarity damage before you detach on.
If you buy Wits 4 instead, shift everyone up one, so the 7 slot matters now, but your first Touchstones moves to 4, and you now have a blank spot at 1 (which you could fill with another Touchstone). 4 severe Clarity damage with still detach your first one.
So, the more Composure you have, the more severe Clarity damage you can take before Touchstones become threatened. The more Wits you have, the more Touchstones you can manage at once.