Why wouldn't you use his fingerings? They work fine for me.

granted, some will work. in my case of a series II alto, alternate fingerings speak better and are far better in tune than what rascher used. they also are "easier" fingerings. raschers feel very awkward.

I agree that rascher's fingerings can be awkward, but I have no trouble using his technique for working on harmonics. I generally don't use them while playing, but I find them to be good exercises while practicing. As someone else said, harmonics are the key to a good altissimo sound.

Problems using Rascher's fingerings may stem from using different horns. A horn pitched in Bb has its own natural fingerings to help achieve top harmonics as does a horn pitched in Eb. For example, on tenor I use the front F key, octave, and side Bb to get an altissimo G (fourth legere line), but on alto I use octave, L1, L3, R1, R3 to achieve its high G. It has to do with datural harmonics of the horn. For starts though, use the excercise detailed above, but play F at the top of the staff. Then switch to fingering low Bb. Try to keep the F while fingering Bb. Achieving this will aid in training your palette and tongue for centering in on overtones and playing in the altissimo register (in addition to improving ear and facility on the horn).