Evaluate Function variable in RPN mode?

[David Hayden]

If I store a function like (X-4)/X in F1, then I can evaluate F1 at different values of X in Textbook mode very easily. For example, I just type F1(0) or F1(3) to evaluate it at X=0 or X=3.

But in RPN mode I have to enter a value into variable X, then recall F1 and EVAL it. Is there an easier way? Since F0-F9 are functions in X, it would easier if they just took their argument from the stack like the built in functions.

Thanks,
Dave