Yes. Currently, there is a limit on the file size currently supported by ProKnow for uploaded files. That limit is roughly 100 MB (which is a very large dose file) and as a rule of thumb, you should aim for a dose file that is 50 MB or smaller provided you still meet the plan and dose requirements.
What can be the cause of a very large RT Dose file? Well, if you calculate dose at very high resolution (say, less than 2 mm), your TPS may produce a very large dose grid and therefore a large exported DICOM RT Dose file. Or, if the bounding box on your dose grid covers a very large patient volume (far larger than all targets and critical structures), then this also increases the size of the dose files.
If your exported RT Dose is near 100 MB (or larger), then you should try to minimize it without losing accuracy. The easiest solution is to reduce the calculation region's bounding box size (i.e. grid extents) to cover all the targets and critical anatomy, but not necessarily cover the entire patient volume defined by the CT scan or external contour. Or, if you have dose grid resolution (i.e. grid spacing) of < 1 mm, there is no added value in terms of resolution or DVH calculation, so if your TPS allows you can increase the grid spacing to 1-2 mm, which is sufficient for most plans, even those with small target and/or OAR volumes.