It depends on your loading technique.
When I'm loading I generally hold the rifle just in the front of the trigger guard with my right hand, resting the barrel on the stand/table in front of me, and load with my left hand.
In the cases where I don't have a stand/table in front of me (or it's too low) I'll support the rifle in my left hand and load with my right hand.
My advice... you have to find what technique works for you and stick with it, but have a backup plan when you're shooting at a range that may be different than your home range.
When I'm loading I generally hold the rifle just in the front of the trigger guard with my right hand, resting the barrel on the stand/table in front of me, and load with my left hand.
In the cases where I don't have a stand/table in front of me (or it's too low) I'll support the rifle in my left hand and load with my right hand.
My advice... you have to find what technique works for you and stick with it, but have a backup plan when you're shooting at a range that may be different than your home range.