Yes you are charged for using the reserve which is an advanced listing upgrade and not included in free listings. Charged at 4% of the reserve price, there is a warning next to the reserve box you fill in, and the fee is displayed at the bottom of the listing form before you click to "list with displayed fees". It's a listing fee, not a selling fee.
Reserves are a waste of money. Just start auctions at the lowest price you would be willing to accept. No one can bid below your starting price.
There is a lnk to the full fee structure on the left of your selling page, under the heading of shortcuts.
