the R isn't pronounced, R+T gives us a sound /ʈ/, but I don't know how to pronounce it
Perhaps wikipedia with it's sound examples can help you?
It's like pronouncing a T, but the tip of your tongue is slightly farther back.
Do you know if it is subapical? If it is then it's a sound accounted for by my mother tongue's phonology, but elsewise I'll have to figure out how actually to pronounce it.
I don't know what that means, sorry.
It means that the tongue is curled back and the T is pronounced with the bottom of the tip of the tongue, not the top. Are the Swedish RT/RN/RS like that?