[XeTeX] how do I embed fonts into a a xelatex generated pdf?

[Adam Russell]

I am preparing a submission to a conference that requires fonts to be 
embedded in the submitted pdf.
Even after a bit of googling and searching this list's archives I am not 
sure how to do this.
I understand that I can see which fonts are embedded using `pdffonts`.
Here is my pdffonts output:
name                                 type              emb sub uni object ID
------------------------------------ ----------------- --- --- --- ---------
BWYDTC+NimbusRomNo9L-Medi            Type 1C           yes yes no       4  0
VBXBTV+NimbusRomNo9L-Regu            Type 1C           yes yes no       5  0
OJQRUO+CMSY10                        Type 1C           yes yes yes      6  0
DDDDNJ+NimbusRomNo9L-ReguItal        Type 1C           yes yes no       7  0
TFUFZE+CMMI10                        Type 1C           yes yes yes     12  0
SLZBCJ+CMMI7                         Type 1C           yes yes no      13  0
FJPKJJ+CMSY7                         Type 1C           yes yes yes     14  0
GXLPLZ+CMR7                          Type 1C           yes yes no      15  0
BYVRVF+CMEX10                        Type 1C           yes yes yes     16  0
KDPCRI+CMR10                         Type 1C           yes yes no      17  0
Helvetica                            Type 1            no  no  no      31  0
FSEEIM+MSBM10                        Type 1C           yes yes no      53  0
Helvetica                            Type 1            no  no  no      48  0
Helvetica                            Type 1            no  no  no      63  0
Helvetica                            Type 1            no  no  no      88  0
Helvetica                            Type 1            no  no  no      94  0
So apparently they are all already embedded except for Helvetica, yes?
So what is the next step to take in making sure all the fonts are embedded?