The locking strip feeds through the little eye so that as the tool opens the channel the locking strip is fed into place.
Given the advice from this forum I purchased a tool with a large handle (
https://i.ebayimg.com/images/g/3vEAAOSwxodgd0JX/s-l1600.webp) and once I got the technic down was able to get my locking strip/window installed in less than 15 minutes. One of learning curve things was removing the extra options for the "eye" piece so that they were not in the way of the tool working as intended.
