Some notes on this:
1. The OR operator functionality, which shows up as parenthesis can be activated simply by clicking where you want the parenthesis to appear. If you click several times, it will cycle between OR "(" and AND "[" operators. Make sure to add both opening and closing operators. This is done right in the GUI, without having to use the Import/Export window. Click in the same places that the "(" show up in the pictures in this thread. I was shocked when I learned that this feature was in MC. I'm not sure if it's documented anywhere or not.
2. The functionality of matching on any from a list of artists is built right into the smartlist rules. "Contains" matches a substring. So if you put "george" there, it will match "George Howard", "George Winston", etc. That's probably not what you are trying to do.
You are probably trying to match a specific list of artists by their specific names. If that's what you want, then change "Contains to" be "Is Any". That will bring up a list of all the artists in your library with check boxes. Just check the box next to each artist you want to match. You only need one "is any" line with all the artists you want to match on.
Brian.