Can some one please advise what size of twintip I should buy?!i have a 12m north rebel and weigh about 83kg.water will generally be flat/choppy.wanting to do free ride/free style.want the board to take me from beginner through to intermediate!cheers in advance

I'm going to leave it to much more experienced guys than me to answer this, but I will say I've ridden only 4 twin tips and all of them were incredibly different. I won't tell you what they were because you don't need influence from a guy as new as me but when asking about size, hopefully the guys who answer will talk about characteristics as well.
1 of the twin tips I rode was so stiff and hard on my knees it wasn't funny
1 of them was soft and nice but doesn't turn very well
My favourite is a wave style twin tip and carves really well and doesn't jar my knees from being so hard.
All 4 were pretty close to the same size as well.

Long storey short hopefully the experienced guys comment on those board characteristics as well as board size.
Good luck

Shinn Dundee is a good all rounder for Perth I have found......