I haven't tried Rv6 yet I'm still using Registax v5. My procedure is roughly as follows:
- Capture say 600 frames.
- Open the video in Registax and scroll through and pick a sharp frame to set multiple alignment points on, then Align.
- Use the Limit button to reject the worst frames.
- On the optimise tab Create a new reference frame from the best 10 frames or so.
- Apply the most appropriate wavelets to the reference frame before continuing. this should hopefully get you the best frame (hopefully better than any you've captured) to optimise to.
- Optimise.
- On the stack page, open the Stackgraph. Use the sliders to select say the best 150 or 250 or whatever to stack, and then for each alignment point drag the difference pointer down till you are stacking the best 100 or 150 or so.

- Stack the image and save it.
- Apply wavelets on the next tab and save it on the Finish tab.
The initial limit cull reduces the number of frame you need to process by getting rid of the worst ones.
The Quality slider on the stack graph lets you select the sharpest frames.
The Difference slider lets you reject the sharp frames that are most distorted. A distorted frame will adversely affect the stack just like a blurry one would.
Al.