I haven't followed the Sony cameras, but I'm assuming that this is a brand new model. According to the published list of supported cameras, that model is not yet supported by Lightroom or camera raw. If it was released in time, it could be supported in the next update. If not then it will be several months before there will be support.
To build on Jim's response, based on past history of LR releases, there's a 79% chance the RX100 Mark V will be supported by the next release of LR. If there is a version 2015.8 / 6.8, it's likely to come out mid-November; the next major version (LR 7) might come out early December to March. Of course, those are just predictions based on past history -- the actual dates could be much different. See Re: Timing of Lightroom releases