Yeah I can't see why Skoda say to put sealant at the corners, the gasket sits fine in the corners just like everywhere else. I did originaly fit the gasket without any sealant on and it still never leaked! It was only after I did the job I found out to put a little on the cam bearings so took it all apart and used a little bit. I never put some on the corners though. No leaks!

Never used any sealant when I replaced the rocker cover gasket on mine because wasn`t even aware it needed doing.  Been running a year now and no leaks.