Ramos.rtw Skyboxes have multiple faces, basically it should look like this when you open it in your IMP
e276144a-e8c7-43f9-98ca-91828ee9f7fc-image.png
If not, then extract your texture from the game as a DDS file, and export it as a DDS file in NVIDIA game texture tools with the same settings as shown in the screeshot
1cb6449c-1f16-431b-b426-ea9abc81eec1-image.png