I find no Platenik's in Strakonice for the time frame you need. Probably a small town nearby.
On Karel's immigration he states he is going to his brother Vincenc Platenik and Vincenc's parents per LDS are Vincenc Platenik and Katerina Kunzl/Kuncl.
There is a 1898 marriage of a FR. Platenik in Strakonice and his father is from Drazejova.