There are requirements where you want to transport variants of your program in your landscapes, instead of the whole program. You can do so by two ways:
1. Using a program named RSTRANSP.
2. Using Transaction SE38/SA38. Select Variants and click Display. Enter variant name. Goto Utilities -> Transport Request. It eventually goes to the same transaction i.e., RSTRANSP.
Enter the progam name and variant name. It will confirm by popping window containing all the variants of the program. Select/unselect from the variant list.
It will then ask for a Transport Request to bind the variant with. Specify the Transport Request. The variant gets attached to Transport Request.