Definitely never feed a ram with ewe pencils - they can cause stones in the urinary system which in the worst case scenario can be fatal.
If you do ever need to feed your ram anything more than hay in the winter you can get a feed called Champion Tup, from Carr's, which is formulated to be safe for all male sheep - wethers as well as entire rams.
At this time of year, if he's inside unable to get out to graze for some reason, then give him hay. When we have snow lying for ages in the winter, too deep for the sheep to scrape through, we give our tups a small handful of the Champion Tup, and in fact that's what we give our primitive ewes and lambs, as it doesn't have the high protein of ewe pencils, which they don't need.