These tips work with some adjustments in the rmPen.
According to a Facebook user:
I got them going: if you look at the head of the nib it's getting slightly thinner towards the “jaw” (to stay in the image…). After using a nail file and making it only slightly thinner it worked. Looks like it otherwise gets stuck after drawing the first line.
It seems that you can also buy the Wacom ACK22201 black (hard) Tips and the Wacom ACK22203 white felt Tips in a 3+3 combi pack as ACK21616.