Thanks for the uncropped version. The left side of the picture has rather pronounced leading lines that were less noticeable in the tighter crop. You will probably notice that the slope, left part of the cliff and the back of the small hill are all pointing to a single small area in the picture, which is near to the river outlet (I presume that is where the water from the waterfall is headed). The eye will be naturally drawn to the spot, so place something there, either when taking a picture or in post processing.
I noticed that in the “raw” image the hill is brighter than the cliffs in the background, this gives some sense of space and distance. In the processed images the brightness is the same, so I didn't notice the hill right away. The usual standard is to “paint” foreground darker and background lighter.
Landschap bij Dinant is a typical example, but in my experience making both background and foreground darker than the middle ground works as well.
I took the liberty with experimenting a bit with your picture. The edits made:
- darkened the background a bit,
- placed a small boat at the leading line spot (yes, it is a bit cheesy),
- cropped the image, so the boat is dead center (vertically)