I am doing the final touches to my trial run wedding cake. The bride wants ribbon at the base of each tier. How do I attach the ribbon to the fondant?

A dab of piping gel works great!

Thank You I don't know why I didn't think of that!

a little cooled boiled water. just brush it on the fondant. it doesn't show through the ribbon or mark it.

Double sided tape also works.
Royal Icing , piping gel, buttercream etc will leave a mark on the ribbon.