I just did the Portuguese (pt_PT) translation for the theme.
You can get the zip file with .po and .mo files at this link: http://www.tugaok.com/rtpanel-pt_PT
Extract the zip and move the files to languages folder of your theme.
You can use it for Brazilian Portuguese too by changing the name of the files to pt_BR.mo and pt_BR.po
However if you want to go further get Poedit program at the net (its free), install it at your computer, open the .po file and edit the translation according Brazilian terminology.
By the way the same applies to any other language, I'm looking for Spanish, French and German translations.
As far as I've seen rtPanel is worth of trouble, I know many themes and I'm very happy with this one.