Re: "Just get any UHS-II V90 SD Card..." - yeah, v90 is awesome if you have money to burn, but honestly, over the years i've found that v60 is usually the sweet spot for these high-res compacts. unless you're shooting 10fps bursts of uncompressed raws (which... why?), you probably wont notice the difference in daily shooting. couple things i've learned the hard way:

• v60 cards are way cheaper per gigabyte
• you can get a ProGrade Digital SDXC UHS-II V60 256GB for a fraction of the cost of those sony tough cards
• buffer clearing on the rx1r series has always been a bit slow anyway... its just the nature of the beast i switched to the Lexar Professional 1800x 128GB SDXC UHS-II V60 a while back and its been rock solid. saved a ton of cash and i havent missed a shot yet. those 61mp files fill up cards so fast, id much rather have double the storage capacity than shave two seconds off a buffer clear i barely trigger anyway. dont let the marketing hype trick you into overspending.

Just got my RX1R III last month and went straight for the Sony SF-G series UHS-II cards - they're pricey but all of the top 10 UHS-II cards that I have tested will all perform well in the Sony RX1R III. With that massive 61MP sensor the Sony RX1R III is capable of producing file sizes up to around 135MB when shooting uncompressed RAW, so you really need the speed. I'd strongly advise against going with one of the cheaper UHS-I cards especially when dealing with the large 61MP files that the RX1R III produces

Just get any UHS-II V90 SD Card. https://www.bhphotovideo.com/c/search?Ntt=uhs-ii+sd+v90&BI=8941&KBID=10361&SID=12345&DFF=d50