Done that without problems from the SNCF web site, I even retrieved my tickets at a machine at the Gare du Nord!
Just click on "France" when you make your reservation, use your US card #, and make sure you note your reservation # in case there is a problem.
Works like a charm. I am not sure of the price difference with Rail Europe, but you should check it out.
[This message has been edited by Droneklax (edited 11-15-2000).]