Never have heard "Triptych for a Witch". But, an epsiode called "Stay Out of Dutchman's Woods" sounds similar to the synopsis you were mentioning. Any man who wanders into "Dutchman's Woods" meets Katrina (again RMT's "resident witch" Joan Lorring) and are lured to their doom! Unfortunately, newlyweds Paul Hecht and Jada Rowland decide to take a picnic lunch into the woods...........

There are a lot of RMT "witch" tales, come to think of it. Some I recall are:

"The House of the Voodoo Queen" (Mentioned earlier in this thread--a good one!)
"Mind Over Matthew" (a rather corny one)
"Mother Love" (creepy "Rosemary's Baby" type of tale)
"The Creature from the Swamp" (Not, exactly, a witch tale, but again Joan Lorring lures a man to his doom!)
"The Velvet Claws" (First rate! --and once done on a episode entitled "Ancient Sorceries" on "Escape")
"Woman from Hell" (A very creepy modern day tale of a coven of witches)

I'd recommend them all (Except, maybe "Mind Over Matthew")