But Lasors seems to say that it has to be applied for "on a separate form" after the licence has been issued.
No, I don't think it says anything of the sort. Here are some important bits:
Applicants for a JAR-FCL PPL
should be aware that they must also pass the practical
Communications test if they wish to apply for the
additional FRTOL, which is a separate licence, required
under different legislation.
Validity - The RTF written examinations and practical
test for a stand-alone licence are valid for a period of 12
months for licence issue. Where a candidate completes
the examinations for a FRTOL in conjunction with a course
of training for a JAR-FCL PPL, the validity of the radiotelephony
examinations may be extended to 24 months from
the date of passing the last PPL theoretical examination,
provided that all examinations are passed within a 18
month period and that application for both licences is
made concurrently. PPL holders who subsequently wish to
obtain a FRTOL will be required to complete the practical
Communications test and apply within 12 months.
So if you apply for the licences separately, both FRTOL exams have to be passed within 12 months of the application.
The choice is yours!