^ it is a fine line - no we don't like threads on how to get high, but there is definite HR value in explaining how to get high safely, especially with fentanyl!
I'm actually not sure on the conversion of oxycone - it is complicated as a lot of conversiuon tables use total 24 hour dose of oxy (presuming you are a pain patient) and of course a fentanyl patch releases a constant amount of fentanyl into the bloodstream - so there is no simple conversion for a one off oxy dose to a patch. As nAON says, a 75mcg patch contains more than 75mcg - as it releases 75mcg every hour and is designed to be worn for 72 hours. The patch also contains a bit extra too - just over 12mg, as nAON says.
If you wear the patch as directed, the fentanyl is released into your subcutaneous patch and continus to release it even after you remove it - so although this is how they are supposed to be worn, if the patch is too strong it is actually very very dangerous. If you are determined to try it that way, I would cut off a very tiny bit and test that first. It takes about 12 hours to reach a steady state too, so don't add any more in this time period... and remember even uf you take it off, fent continues to be released.
Depending on the patch type you can also smoke it (if it is a gel reservoir) or cheek/gum it (stick it to the inside of your cheek/gum) but these are very dangerous too as a lot of fent is released at once.
If you smoke it, use the tiniest amount of gel possible and vape it off some foil. The advantage of this method is it hits you instantly so you can titrate it. The disadvatnage is it is easy to get too much on one go, which obviously can be exremely dangerous.
If you cheek/gum it, nAON is right, you certainly don't want more than 1mg. i'd probably cut the patch into 16 and try a 16th. It doesn't hit instantly, so definitely leave it 30 mins at least before you redose. Titration is harder than smoking, but this is the best method if you don't have a gel reservoir patch but a plain sticky one as this sort can't be smokwd really. Remember, smoking it causes you to inhale p,astic fumes.
Overall - please be extremely careful. Start with a very, very tiny bit and wait long enpough before redosing. Fent is notorious for overdoawa and can be lethal. Definitely don't take any other downers (alcohol, benzos) either...