Re: siguard rachers top tones for sax study book
Yes, and Absolutely.
Altissimo is more about embouchre/mpc than fingerings, though they do work in conjunction. (There is no magic formula - you have to see what works for you on your horn).
The book has great exercises to guide your development of a proper embouchre and technique. The F# key may come into use at some point, but there is plenty you can do without it.
I actually rarely use the F# when playing altissimo. I work more from conventional fingerings high C and below. I may experiment by adding right hand keys to affect tuning.
With altissimo, you're working off the fundamental as suggested by the base fingering. I find it easier to work off mid-range fundamentals than fundamentals above, say, high C.
What kind of mouthpiece are you using? Some altissimo is possible with any mouthpiece, though mpcs with a high baffle, smaller chamber, or shorter table curve make it easier for altissimo to "pop out". Don't get too wrapped up in the equipment chase, either.
Get the book and focus on the exercises more than fingering advice you may find from other sources. Gotta get the technique right before worrying about fingerings.