The former Parramatta Eels player moved into the number 1 role late on in the campaign, after featuring mainly on the wing and at centre earlier in the season.
“I would have liked to have moved to full-back earlier this season but Chris [Chester, Hull KR coach] and the boys have their structures and plans and I’m just happy I got a run there,” Sio told the Hull Daily Mail.
“Hopefully, I’ve shown enough that I can play there more next season.
“I’m pretty stoked with how many tries I scored on the wing but it wouldn’t be possible if it wasn’t for my team-mates. Wherever Chris Chester wants me to play, I’ll give it my all for the team.”