I've recently come across studies that showed that Estrace and Provames (oral estradiol tablets) taken vaginally in genetic women were effective, up to 11x more than oral, in terms of estradiol levels. I wouldn't see any reason, then, to why rectal couldn't just be as effective since both routes yield similar results when used for hormone replacement therapy in women. If you aren't bothered by this for psychological reason (which I also understand if you would, but I'm not) and prefer this to sublingual (because there is no risk of swallowing and the inconvenience of keeping it there for so long), then this is an option. You just put a little KY gel on the anus (which is safe since it used for rectal thermometers) and insert the pill inside but be sure not to insert it too deep, just enough so that it well placed inside and be comfortable for you. Too deep and it will be absorbed into the portal vein going to the liver and then, it will be metabolized like when you swallow it.
If placed just near the entrance but away from the anus (where you can feel more space) , the pill will melt, dissolve and be absorbed directly into the blood (inferior and middle veins vs superior vein) while giving more constant levels vs. sublingual where levels peak the first 1-2 hours and then exponentially (very quickly) decrease. Levels will be quite high too. So you can take very little and have significant effects.
With rectal, you can take it twice daily vs. sublingually, where you need to take it more frequently to avoid too much fluctuation in levels which may cause neurological side-effects (i.e. PMS).
