How to use the feature "use external program"?

[Z403]

Hello all

I've just said Hello to GoldenDict. in fact I'm getting used to it sooner than it seemed to take.

I have installed espeak and get it run by command line like this:
[...]\espeak.exe -v en "WordToPronounce"

What am I supposed to enter into "use external program" field to make it work?
and what to use Microsoft Sam?
BTW why isn't the windows native API option working?

thanks in advance.