The microphone hole is the center hole flanked by two larger holes.

Align the adhesive strip to the bottom edge by positioning the microphone notch over the microphone hole.

If your iMac does not have a microphone hole, align the right end of the strip such that the L-bend sits next to the right vertical adhesive. The L-bend should not overlap the right vertical adhesive.

The adhesive tears easily. Be careful not to pull on the strip with too much force.

Once you have aligned the strip, carefully set the left exposed edge onto the iMac to secure the alignment.