Tips on working with a ring stretcher

The advertisement says that the stretching works as a function of
burnishing. Will this mean that I will not need to anneal the
metal periodically as I work the machine over it?

Sadly, no. The burnishing statement maybe refers to the fact that
you may not need to re-polish a ring after stretching, but if you
stretch a ring it will certainly get harder.

Any other tricks or tips you would recommend for this little
beastie? 

I use mine as a miniature rolling mill for thin wire too, but found
it difficult to judge how much I had tightened the roller. So drew
some graduations on a strip of paper and wrapped and glued it around
the handle that is used to tighten the roller. Voila; repeatability.

Regards, Gary Wooding