If you have the newest Peak Design Anchors (launched in late 2017) then you can attach the Anchor directly between the L-bracket and your camera body (looping the Anchor cord around the camera connection screw). Details on that are here. You can also purchase a 4-pack of new Anchors here.
Older Anchors, and Additional Options
If your L-bracket has a built in hand strap loop, then you can attach the anchors directly to the bracket via that point:
If your L-bracket does not feature a hand strap loop or if you want to have the ability to use Capture as well, then you would attach our quick-release plate to the auxiliary tripod hole on the L-bracket and attach the anchors to the plate.