呃.... 我不清楚為什麼你的系统沒有 rdesktop 的 manual (我用的不是 Debian)。
不過這裡有 manual :
http://annys.eines.info/cgi-bin/man/man2html?rdesktop+1
(Google 關鍵字: man rdesktop)
-g <geometry>
Desktop geometry (WxH). If geometry is the special word "workarea", the geometry will be fetched from the extended window manager hints property _NET_WORKAREA, from the root window. The geometry can also be specified as a percentage of the whole screen, e.g. "-g 80%".
-f
Enable fullscreen mode. This overrides the window manager and causes the rdesktop window to fully cover the current screen. Fullscreen mode can be toggled at any time using Ctrl-Alt-Enter.
-a <bpp>
Sets the colour depth for the connection (8, 15, 16 or 24). More than 8 bpp are only supported when connecting to Windows XP (up to 16 bpp) or newer. Note that the colour depth may also be limited by the server configuration.