Sigma has released a plug-in for Photoshop that supports development of X3F.RAW files from recently-released Sigma cameras.

This Plug-in is available to customers who own the DP Merrill series, dp Quattro series, SD1/SD1 Merrill and sd Quattro series cameras. The new plug-in does not support X3I files taken with SFD mode or X3F.RAW files taken with the SIGMA SD9, SD10, SD14 and SD15 as well as DP1, DP1s, DP1x, DP2, DP2s, and DP2x  cameras. The plug-in requires the 64-bit version  of Photoshop CC, vintage 2017 or later.
Click here to download the plug-ins for Windows and Mac operating systems.