I would try the MapnikRasterizer. Just make sure that the vectors are on top of the raster.

How do you make sure the vectors are on top?

The ordering is controlled by the input ports on the Mapnik Rasterizer, with the top port being drawn first as the bottom most layer.

Probably a good idea to check that your raster and vector are in the same coordinate system also

Thank you. I've done the everything just not quite seeing the lines appear ontop of the rasta. It seems as if the lines are condensed together at the top left of the rasta once they are combined. Image below.

The yellow lines now seem to be top right? Why are they not overlayed to look the same as above?