Hi appointment-insect,
Thank you for your reply.
The Texture and the Ramp node have options for using a specific UV tag. I mention both, as they use a different name for the field. Uv-Channel for Texture and Texture Space for the Ramp Node.
https://help.maxon.net/r3d/cinema/en-us/Default.htm#html/Ramp.html?Highlight=ramp%20
https://help.maxon.net/r3d/cinema/en-us/Default.htm#html/Texture+Sampler.html?TocPath=Shaders%257CTexture%2520Shaders%257C_____13
Here is an example
https://projectfiles.maxon.net/Cineversity_Forum_Support/2024_PROJECTS_DRS/20241017_CV4_2025_drs_24_RSuv_01.zip
Select the Texture or Ramp Node, and while the Redshift render is active, drag different UV tags into the fields.
My best wishes