I got most of it to work.  I am enclosing a little starter document for others.    as a beginner, I could not figure out

* how to create larger and smaller font text

* how to underline text

* how to put a table and preformatted text on the same slide.

* how to create footnotes (not endnotes)

* how to create incremental or paused content.

but it looks like it is enough to create simple powerpoint presentations with markdown.  thanks, john.