a little review of the lensmate rx100 VI quick change filter adapter (52mm)
I went ahead and bought the lensmate rx100 vi filter adapter set and installed it on the camera. according to their amazon and product description that 1) there is no flash blockage throughout all focal range when the filter holder is removed. but the description is inaccurate. this is my finding with the filter holder remove and just the low profile receiver in place using flash. another inaccurate product description is 2)"the receiver is smaller in diameter than the end of the lens barrel." well i found that it's not, the low profile receiver diameter is bigger than end of the zoom lens barrel, which results in flash blockage.
good thing is that there is no vignetting throughout all focal range. the only problem is the flash blockage at 24, and 28, and 35 mm (but it's not very noticeable at 35, but its still there, i didn't upload the pic at the focal range)

24 mm focal range with flash on (filter holder adapter is removed and just the receiver in place.)

at 28 mm

24 mm

28

the filter receiver in place glued on to the camera with the 3m adhesive. the description said the receiver diameter is smaller than the end of the lens barrel, so there is no chance of flash blockage. but clearly, you can see it overlaps.