Ok, the 3 major qualifiers for sendkey are:
For mapstyle in S&T, you press Ctrl M on the keyboard, so the sendkey button command in RR would be:
To bring up the file menu, you would press the keys Alt F so the send key would be:
Now, say you wantet to bring up the file menu, to save something. On the keyboard you would press Alt F and then then S. The sendkey command for that would be:
Have a look at THIS PAGE for other keys, and how to use them.
As for it opening multiple instances, that sounds like the window title is not exactly correct. RR keeps track if a program is running already, by looking for the title of the window, and that is also how it embeds it.