Basically, roses can handle bark mulch. But still one needs to differentiate: Roses have deep roots and get their water and nutrition from deeper soil layers. So if you start to give humus on the top layer the roses will build roots which are very frost-prone. So they are not that frost resistant anymore. So if you decide to mulch, make sure that you use bark mulch which decomposes slowly. This way you do not have too much humus and you can avoid the problem described above.
The mulch will change the ph-value of the soil, it will get more acidic. So you have to lime the soil as roses prefer basic, not acid, soil. During decomposition the mulch drags out the Nitrogen of the soil. So you have to give nitrogen and potash as well. My suggestion is to fertilize with 50-70 g/m² nitrogen and 30-40 g/m² potash – this comes on top to the usual fertilisation.