I'm not sure if this is the right place to post this, but on the Extend a partition page http://www.runeaudio.com/documentation/troubleshooting/extend-partition-sd/ the correct partition type is 83, which in fdisk 2.25.2 is a Linux type partition. The number 82 which is suggested in the page is a Linux Swap partition type.
EDIT:
I'm using the latest 0.3beta version for RaspberryPi. Maybe this is relevant for the stable version?
Cheers,
dum