dual booth openSUSE 13.2 on Mac OS X 10.6 partitioning problem

I have been struggling to dual boot install OpenSUSE on my macbook pro running OS X 10.6 (snowleopard).
I have installed rEFIt and also resized my MACINTOSH HD using disk utility. However, when I proceed in openSUSE installation and get to partitioning section I get the message that the /root is not assigned and the installation will fail.

I selected the “expert partitioning” and can see my drives “sda, sda1 (rEFIt), sda2 (MAC OS) and sda3”. However, I have no idea how to proceed from here and assign /boot /root and install openSUSE on sda3.

I would highly appreciate an step by step help as I could not find anything online.