Hi Joerg,

If you want to use soundfonts to make an audio recording of your work, you can use a free work-around if your sound card does not support soundfont use. There is a product called SynthFont, which is free (or donation-ware), available at www.synthfont.com. SynthFont reads .mid files, and you can assign whatever soundfonts you want to each instrument. You can also use it to render a file to .wav or .mp3 for sharing an audio version with others.
So your process would be to
(1) create and tweak your file in Composer
(2) save it as a .mid file and
(3) use SynthFont to render the audio file.

We're working toward better all around sound support for Composer, but the above would be a free and relatively easy solution at this point.

ttfn,
Sherry