What whistle/flute for "The River"

So, my daughter was asked to play the flute part for “The River” in church this coming Sunday and given a recording so she could hear what it sounds like. She played it for me this morning but it’s a whistle and not a flute that’s played. I haven’t seen the music but called my brother-in-law (the music director) who said the tune is in F. Heather plays a keyed silver flute and I’m afraid that it will be a little cold for this piece, especially with the singers I think they will be using. Have any of you played the part and if so, what instrument did you use? Would a keyless C or F flute work? I don’t have either flutes or whistles in those keys but assuming I could acquire one in the next two days, what should I try for? Oh yeah, any thoughts on which would be easier for her to learn on?

I can think of several songs called “The River”. Could you be more specific?
But if it’s in F, you could use a C whistle if it does not go out of range… (the C
below the staff to the B above the staff)

I would transpose it up one step so she can think in the same fingerings as the
silver flute.

It starts like this:

To the river I am going bringing sins I cannot bear
Come and cleanse me, come forgive me Lord I need to meet you there

That’s all I can remember, maybe it’s not a contemporary tune at all?

Ok, the tune is by Brian Doerksen on his “Today” album…

That was enough for a Google search. It seems to be a contemporary tune,
yes, written by Brian Doerksen (what a name!) From the sample lead sheet
I found, it looks like a C whistle is a safe bet.

Also, have you tried asking at praisewhistlers.org? Far more likely someone
there has played this on whistle/flute.