DEAR HARRIETTE: I'm about to host my own birthday dinner. I want to invite a few friends out to a nice restaurant, but I'm stuck on how I should split the check. Do I pay for only my portion and expect everyone else to cover their own? Or should I ask my friends to split the total cost equally? I don't want to be tacky. How do I let my guests know that I do not plan to cover everyone's meals? The …