How to install standing seam metal on a flying gable

A gable trim where you bend the miter cut of the standing seam panels down into a channel or around a cleat or lock is best. But, you must have a brake long enough to bend the panel and even then it's hard to do this without forcing ripples into the panel. The other option is a very low profile F-Channel style of gable that the cut edges of the panels just slip into and then are sealed.

To add to Todd's comments, there are hand rollers that assist in turning the diagonal cut either over the edge and onto the cleat (or "D" style drip edge), or turned up into a "channel" edge trim that "gutters" to the eave. Most manufacturer's will have a suggestion as to which detail would work best for their given system.