1. I opened SW-12 and sketched the desired profile there.
2. i Saved it as Library feature file in Weldment profile folder as 'round1'
3. Then I opened SW, Went to weldment profiles in the weldement workbench.
4. The option 'round1' was visible in the options and I selected it
5. But when I clicked on the drawing to apply weldment, there was an error -" this library part feature is empty"
follow these instructions:
1) after you make the sketch for the part and hit the check mark. (close sketch). save as .sldlfp .
2) right click on the sketch name in the column on the left . select add to library
3) save again and move to the proper directory for solidworks to find it.
Rollin Shultz advice works. still think this could be a lot simpler.
Side note: make sure your sketch is a closed contour not a "thin feature" Seems obvious but when dealing with thin materials its easy to forget.