Haskell QuickCheck generate random data for function with many input variables

Haskell QuickCheck generate random data for function with many input
variables

I have a function with the following type signature
rndListIndex :: Double -> Double -> Double -> Double
rndListIndex maxIdx r1 r2 = …
the first input should be a value coming from a non-negative integer
the second and third input are required to be within the closed interval
[0.0,1.0] otherwise the function makes no sense
the function has the property of
prop_alwaysLessThanMaxIdx idx r1 r2 = (rndListIndex idx r1 r2 <= idx)
how do I generate random data for maxIdx and r1,r2 separately; I know of
the function choosebut do not know how to use it with more than one input
variable.
For now I have tested the Property with fixed idx, which is not the way it
should be tested.