Potisek was an often last name in 19th century in area in which my predecessors lived, so I can construct a couple of family trees. If you let me know a name of one of your male predecessors and his birth date before 1895 and if I find him in my database I can help you.
But I can speak about Potisek in general. The origin of the last name Potisek should be the village Velika Kostrevnica (municipality Šmartno pri Litiji) in central region of Slovenia, 30 km eastern from the capital Ljubljana. I suppose this is the only origin, because the name is not very often (187 in Slovenia in the year 2010, 70 % still in the central part) and can be followed in this village to 1700, at that time present with 2-3 families. It was most often in the second half of the 19th century.
By myself there could be two theories about the meaning of this name. Firstly, near Velika Kostrevnica on the hills there is a part of one village with the name Tisje. The first Potisek could be from this local part. The second possibility could arrive from Slovenian verb potisniti (to push). So, this should be a person, which is pushed out of the village or to the edge of the populated region.
Another version of this last name – Potisk, which is often in the northern (Styrian) part of Slovenia, probably does not have the same origin as Potisek.
I know for two families, which members went to the US, as I wrote about in my above issue. If your predecessor is one of these people I can construct the family tree.