Please see the sample file attached to this post.
The Hair settings are very simple. No Children. Hair dymanics have been turned on (press play on the animation for a few frames for them to bend downwards). The segments of hair have been set to 10.
The Shape of the hair strand has been set so that the tip should be very thin but the root should be ticker.
In RPR renders the hair dynaimcs and segments correctly but does not respect the hair thickness settings.
RPR close up render:
Cycles close up render:
Resulting Cycles full render:
Resulting RPR full render:
The actual hair from RPR is very nice looking except for the fact that it does not thin towards the tip.
Sample file attached for testing below.