Used two hands.
Assisting himself does not disqualify him from this thread for two reason.
1. He is not Naruto and therefore was never qualified for this thread to begin with.
2. The manner in which he assists himself does not violates the requirements stated in the Original Post. He does not create a Rasengan while under the influence of a tailed beast, nor does he create a rasengan while being assisted by a clone.
/endof