What is the correct way to set your silverware to indicate that you are finished with that course.?

Hide them under the lumpy mashed potatoes.

Maybe because I'm left-handed, or maybe because I'm English - but when I finish with a course I place my knife and fork together with the handles at 5 o'clock and the business ends at 11. I try to time my 'bathroom breaks' so that they don't arrive during courses, but I have been known to make a rather rapid exit once I have finished eating. A simple 'You will excuse me for a moment.' to guests in immediate vicinity and I'm off! (usually for a fag)........oops can't say that here, I mean a ciggy.

You place knife and fork together at 6:30 or thereabouts (if the plate were a clock).

From what I understand, the signal for being finished with the plate is to place your fork face down on the plate, across the center. Any other configuration and the server should not remove the dish.

In USA, the correct way (as far as I know) is to lay the fork and knife across each other near one end, on the plate. To indicate you're NOT done, lay it back down by the plate.

From what I know you have to put the fork and knife on the plate cress crossed

You should place your silverware side by side, in the centre of your plate. If you have to go to the bathroom during a course, or are just taking a break, then placing your cutlery with tips touching, like an inverted V, tells the waitstaff, you're not finished.