[XeTeX] \newfontinstance

[Martin Henning]

moin,

i am desperately trying to craete a new command, which inserts a  
small \textregistered. i'm using charis SIL and the (R) is really big  
and ugly. i manage to create the command, and use it, but  
unfortunately after fist usage, the whole rest of the document is in  
the font which has been defined in \newfontinstance, so i'm obviously  
doing something wrong. looking through the fontspec documentation i  
can't seem to grasp my mistake... it all looks the same!

currently i have something like that:

\newfontinstance\trexfont{HiraMaruPro-W4}
\newcommand\trex{\trexfont \textregistered}

secondly: i also have a new command for sidenotes, like in the  
fontspec-documentation. somehow i can't use italic-font in the  
\marginpar's - wonder why? is it per default turned off somewhere or  
do i have to explicitly name the italic font in the \newfontinstance  
for my side-note-command?

a little confused but happily unicode-TeXing so far...

martin, moscow