RF isn't happy with terrains and outdoor scenes, however it is possible.
OK here's a rough guide but please experiment it's the best way to learn.
You need the following 4 programs.
L3dt its free get it here:
http://www.bundysoft.com/L3DT/downloads/standard.php
T2 Also free get it here:-
http://www.toymaker.info/html/downloadT2.html
Milkshape $30 worth every penny and an invalualble program for RF, it's easy to learn and use, It also has a 30 day trial. Get it here:-
http://www.milkshape3d.com/
Equity 7c Free get it here:-
http://sourceforge.net/projects/rfxtools/
L3dt:
Export the heightmap as .bmp
Export the textures,lightmap and terrain normals as .bmp
T2:
Make a new project
click file -> Load New in the heightfield and load your height map.
click new texture in the texture and load your texture bmp file.
Click create.
Set output texture to the size you want the default is 256x256.(It must be square
and a multiple power of 2 ie 128x128, 256x256, 512x512 etc)
Tick the box slice textures and make it 2 slices wide and 2 slices high.
Click Go.
When it has done its calculations click Show Mesh.
Make mesh dimensions width 32 height 32 (these dimensions should be the same
high as wide but they don't need to be a power of 2. Bigger numbers will create more polys
smaller numbers will create less polys 32x32 will make 7688 polys, experiment here to make your
lods. You can go higher than 32 x 32 but not recomended for RF, EXPERIMENT with the figures)
Make the world units width 1024 height 1024
clear the boxescreate one mesh and create one texture.
make number wide 2 and number high 2.
click OK.
When the view comes up click export.
Tick the 3ds format in export format.
Clear the box Swap Z and Y. (very important).
Click ok.
Name your file and save.
Close viewer and close T2.
Open Milkshape
Import your 3ds file.
You should have a file that is 7,688 triangles split into 4 groups.
Now for the tricky bit.
Make sure you have saved your MS3d file as ALL.ms3d.
go to groups and select mesh0
click edit -> Select Invert
Press the delete key on your keyboard to delete what you have selected and
you will be left with the top left hand quarter of your map.
Delete the materials Mat1, Mat2 and Mat3
Save AS TL.ms3d
close this file.
Open All.ms3d
Select mesh1 (Bottom left) and do what you did with mesh0 only deleting Mat0, Mat2 and mat 3 and saving as BL.ms3d
Repeat for mesh3(top right) and mesh4 (bottom right). Deleting the materials you dont need.
Now build your actors in Equity from the MS3d files, load them into RF and line them up so they join as seamlessly as possible.
I hope this helps.