Here's a video for directions of the proper procedure for use of Klotz Foam Filter Oil.
Wash filter with Klotz KL-608 Air Filter Cleaner to remove dirt and oil. Shake well, and apply Klotz Foam Air Filter Oil evenly on new or cleaned filter; squeeze out any excess oil. Excessive oil may cause engine to run rich momentarily. Never operate engine without air filter and filter oil.
Many of the articles compiled here where written by Bruce Mallinson. Attribution to other contributors is given in the specific articles.