The Rolleinar for the taking lens is built like a filter. It has a male bayonett on the rear side and a female one on the front side. You can attach filters to them. Just make sure to first mount the Rolleinar lens, then the filter.
The rolleinar part for the viewing lens has no front side bayonett, so you will have to set the polfilter by just looking through it.
My only filter without the front side bayonett is the polfilter.
The whole system of accessories (filters, shade, rolleinar) is well constructed, but you have to practise a bit. For example, I always use the lens shade. When I want to add the rolleipol, I have to adjust it when it is on the viewing lens, unmount it, unmount the shade, mount the rolleipol on the taking lens, remount the lens shade.
The cheapest way to get filters is in combination with a second 2.8F in a less-than-perfect condition: I now have the lens shade, lens cap, a set of B&W filters (red, orange, green, yellow), a soft filter, two rolleinars, the polfilter and a rolleifix plus the original boxes for everything. I use all of these occasionally (except the soft filter, but you can remove the glass and fit something more useful in the aluminium ring). These things alone from several internet stores would have been more $$$ than I could have justified.
When you want to use a neck strap with your F, get into this topic. It is not *that* easy to attach a normal strap to it.