Depending on the RX100 version, it should be supported since 5.5 the latest (for RX100 III) and there would not be a need for any prior DNG conversion.
If it's a RX100 IV you will have to wait because it's not even in the list so far. It probably will be supported in LR 6.2 / CC 2015.2 and in the next release of the DNG converter which you will need if you like to stay on LR 5.x..
i can't import my raw files, Sony RX100, on Lightroom 5. Because of that i downloaded 5.7 and a DNG plug-in. Still i can't import. What more can i do?
What happens? What is the complete unedited exact error message?
LR 6.1.1 has just been released and is supporting the latest RX100 version.
You may wan to update ...