Very interesting; so is this RSX 100 cross-processed in C41 to yield a negative, and then printed on RA4? If so, I'm surprised the contrast turned out to be so well-controlled! Congrats, it's a very nice print indeed.
Yes indeed, this is cross-processed RSX100 printed on RA4.
Since I've been using this combination since before RSX has been discontinued (about 20 years ago) I've become quite good at contrast control. In that case it was a bit of pre-flash, and loads of dodging and burning. Fortunately this did not require a contrast mask!