I have customize my KB so I only put the cursor on the frame and hit “E”. Then I look at the folder where I want to save it. There is an option where you can add a copy of the still into the project.
You can find it at File>Export>frame.
Frame treatment: (Top)Clip>video options> select what you want here.
The problem I had found when adding stills into the timeline is that the stills shake a lot but only I noticed this movement when the DVD is already burned. Never before!! I had to applied “deinterlace” or any other treatment to all stills one by one, then burn the disc again (I use Encore) to correct the problem. Sometimes any other still shake besides all.