TeXShop ⇒ Thai support for Texshop?

[nklohit]

I've already installed and am trying to use package "thailatex" via

\usepackage[thai,thainumber]{babel}
\usepackage{thswitch}

but when I type in thai, the resulting pdf shows nothing but "??????" .
Is it possible that Texshop doesn't support thai font?
I'm trying the UTF-8 unicode but nothing changes.

Am I to modify some prferences? Or anyone can suggest another front-end that support thai?

Thanks for all replies