Although peanut butter is an excellent way to get a pill 'down' a dog, I'm not so sure it could be counted on to get an UNBROKEN pill down a horse, because anytime a horse gets something edible in its mouth, the instinct is going to be to CHEW it, and if they get it the 'blob' of p'nut butter over to their molars, well....
If you don't want the horse to be able to 'chew' a pill, you will HAVE to get it far enough back that the horse immediately 'has' to swallow it whole, which isn't easy, even on a mini. A 'balling gun'(which is what the basic implement for this purpose is called; the 'pill poppers' a just a form of this), that is made for other livestock, WILL probably have too large an opening to 'hold' a small, 'human-sized' pill inside of it until you can get it back far enough into the throat;they are made to 'hold' relatively large boluses/pills, and what is likely to happen is that the pill willl fall out of the implement before you can get it where you want it. Jill, I don't think that choke would be a problem, as what you are putting back there is so relatively small; choke is almost always caused by something of some size, and/or that won't 'slide' easily down the throat.
Balling guns are trickiest to use successfully in horses, because horses have such a full complement of teeth, compared to most of the other animals they are used for(cattle, sheep, etc.) I'd have to see the ones for dogs to see if I thought they'd work for minis; I still have a couple of 'big' horse-sized balling guns around somewhere, but haven't tried to use them in MANY years.
I really think the 'best' way might be pretty much as Rabbit suggested- dry your hand, take a firm grasp on the tongue and bring it out one side of the mouth, then use your extended fingers to push the pill 'way back in the center of the throat, release tongue, elevate muzzle and massage throat to encourage an immediate swallow. Lubing the pill just a bit might not hurt. This likely won't be easy; horses aren't usually very cooperative when it comes to things like this! But if it is IMPERATIVE that a pill 'go down' whole, then you have to do whatever will yield that result!
BTW-I have had good results using ranitadine to treat presumed ulcers. When I had to use it on my miniature gelding(34", @ 250 lbs. in weight),I crushed up @ 8 75 mg. pills, added just a bit of water, administered it w/ a dose syringe daily for, I think, three weeks to a month. When my full-sized Paint mare showed classic signs, mainly loss of interest in her hay(and she was ALWAYS an eager eater!), and general depression, I hauled her down to town to my vet. We didn't scope her, but presumed ulcers based on her symptoms, and she was prescribed 'horsey' ranitadine-LARGE pills, that I crushed and gave in the same way, for a month. By the end of the second day she began receiving the ranitadine, her appetite AND general happy demeanor were back, and she never had any more issues. I did change her feeding routine a bit, and added @ 3/4 cup/day of corn oil, because I'd read in Equus of a study that suggested that a good amount of daily corn oil might act as an ulcer 'preventative'. I still give a daily recommended dose of U-GARD to the miniature who apparently had ulcers, and so far, so good.
FWIW, from my experience.
Margo