In split view, the graph area shows each graph in its own row, which is the extension of the signal's row in the signals view. The vertical scales of the individual graphs adjust automatically, so that the entire graph computed so far fits in the row. Split view is typically used when you want to have an overview of the trends of all signals in view.
If you drag with the mouse horizontally over the graph area, the graphs will zoom in horizontally such that the area covered by the mouse will fill the whole graph area. There is no way to zoom in vertically or increase the height of the rows in split view in the current version of RTflow. To zoom out again, right-click in the graph area and select one of the following: