Currently the only way to debug in RTVS is to first attach the debugger and then source the file, as shown in this official manual. However, this is rather inconvenient, since my script usually expands to hundreds of lines and it will take forever for the debugger to execute to the breakpoint, which usually at the last of the script.
The only workaround I can come up with now is to comment all the above lines before the codes of interests. But, is there any elegant way to achieve that?