Joules, the way it works at R&S is that if the car sells on the auction block the buyer pays 10% commission and the seller pays 10% too on the final auction sale price. So R&S effectively get 20% commission on the sale price.
However, if the car doesn't hit the reserve, then the car goes to a "Post sales" tent where R&S will generally waive the buyers commission fee altogether, but not the sellers fees, effectively cutting the total commission on the car in half to help bridge the gap and hopefully sell the car. Actually, once the car goes to the Post auction tent it seems to be a free for all where whatever deal R&S can work out to sell the car they just might do, knowing its their last best chance to make some commission.
One point worth making is that if you try to sell your car at R&S and it doesn't hit reserve and becomes a "No sale" and you bring the car back home, R&S keeps the title for 90 days. If you find a buyer during that 90 day time they will charge you commission. That's the fine print that I did not initially see.