After each meal, it is a basic and cardinal rule to leave your utensils side by side to signal to the server that you are finished eating and that the plate could be taken.
The best way is to leave your fork and knife together, side by side where would have been four o’clock if you think of your plate as a clock face. In more formal dinners and generally in Europe they are also left at six o’clock position.
If soup or dessert is served in a deep bowl, cup on another plate, place your spoon on this underplate when you finish. If the bowl is a soup plate, ( wide and shallow) leave the spoon in the bowl.
When you pause to take a sip of your beverage or to speak with your meal companion(s), place your knife and fork on your plate near the center, inverted V and the tips of the knife and fork pointing toward each other. You may also rest your knife slightly diagonal on the top right rim of your plate with your fork laid nearby. That signals the trained waitstaff that you are not ready to have your plate removed.