To find the correct combination of plates that results in a five-letter palindrome, let's first understand what a palindrome is. A palindrome is a sequence that reads the same forwards and backwards. Given the initial plates \(\boxed{A}\) and \(\boxed{D}\), we need to add three more letters from one of the options so that the entire sequence forms a palindrome consisting of five letters.
Therefore, the only option that results in a palindrome is the second option.
The correct answer is: \\(\boxed{R} \quad \boxed{\rotatebox[origin=c]{180}{A}} \quad \boxed{R}\\)