Do not try to use the skills menu until you receive the second message. A second message will inform you when the process is complete. When you drink the potion, a message will inform you that the process has begun. The potion removes the perks you've bought as you've leveled up and refunds you the appropriate number of perk points. If you're having bad luck finding it in stock, Elgrim in Riften is guaranteed to have a few available.
It adds a new potion, 'Draught of Fate Unwound,' to apothecaries' inventories via leveled lists (so it should show up on any of them). However, users of SKSE version 1.7.0 or later will enjoy a BRAND NEW FEATURE of 1.4, namely universal compatibility with any and all mods that make changes to the skill trees. Adds a potion allowing you to respec your perk points.
