How to set HF1 or HF2 direct sampling, not the IQ mode Direct Sampling

[waterwin]

Mode has 4 settings (not 2), 0 = RF Input, 1 = IQ (HF1+HF2) direct sampling, 2 = HF1 direct sampling, 3 = HF2 direct sampling
even though the API differentiates only 2 settings //set rx direct sampling mode: 0 - disabled (default), 1 - enabled
How to start the separate HF1 or HF2 as can be seen possible in for instance HDSDR.

Thank you.
Erwin