Every once in awhile I'm asked to add a fondant "ribbon" accent around a cake. Since I don't use fondant alot I was wondering how the experts match the seams and make those seams look "seamless". Thanks

I never tried to make it look seamless.  However, I frequently designed it so there were flowers covering the seams.

The best you can do is overlap the ends, cut thru both with an Xacto, then peel away the excess from both sides.  At least then the two ends butt up against each other cleanly.