C-c C-e C-t runs the command ess-build-tags-for-directory

Ask for directory and tag file and build tags for current dialect.

Afterwards, use M-. to navigate to a tag. M-x ‘visit-tags-table’ to append/replace the currently used tag table.

If prefix is given, force tag generation based on imenu. Might be useful when different language files are also present in the directory (.cpp, .c etc).