Yes, it is very simple:
One downside to this simple approach is that it will repeat the process every few milliseconds you hold the F1 key down. To correct that make a bool variable called F1pressed or something and set it to true at the end of the VK_F1 case statement, then code a WM_KEYUP the same as above just make it so it sets the bool variable to FALSE. Then set up an if statement around your help code to check if the bool variable is TRUE or not. I hope you get this!
//Inside the message switch in the main window loop