If you're upgrading to rTorrent 0.9.8 from 0.9.6 you will find that your old .rtorrent.rc file is no good anymore because the settings have changed in the updated version. You'll need to grab the new version of the .rtorrent.rc file and configure it accordingly, which is available from:
https://github.com/rakshasa/rtorrent
Alternatively, the SARPi 'Install rTorrent on Slackware ARM on the Raspberry Pi' guide has been updated along with the packages required and the .rtorrent.rc config file. Available here:
http://sarpi.fatdog.nl/index.php?p=rtorrent-arm