I have no idea about the heath benefits of using seasonings in chicken feed but the hot pepper for rodent control doesn't work, just an old wives tale spread by well meaning people that have heard of it  and consider it plausible.
There is one sure way to keep rodents out of feed; buy a rat proof chicken feeder.  That is a treadle feeder with a spring loaded door to prevent the rats from just pushing the lid in or up, it has a narrow and distant treadle, and must be all steel, no plastic.  No overhead lids.
You must have mostly adult birds, full size birds, because the only way a treadle feeder is rat proof is if there is a big difference between the weight and reach of a chicken compared to the rat.  Tiny silkies and bantams might not weigh enough to use a treadle feeder by themselves but will learn to eat when another hen is eating.  No chicks or poults either, too dangerous for them.  You must also be willing to follow the instructions to the very letter and ask for help if you are having problems getting the chickens to use the feeder.  
Picking up feeders before dark helps but it also teaches the rats to eat during the day.