Box 14 RI SDI not shown on W2

As long as you have backup to indicate what your RI SDI is, then you may go ahead and enter it in manually. Keep the backup for your records.

Thank you; I needed confirmation that it was ok to manually enter add'l info on an employer issued W2

In addition, I would also ask employer to issue a corrected for W-2.  That way, they will notify IRS of the correction, as well.

@user3446170

Thank you Cynthia, excellent advice, however employer refuses to issue corrected W2's because Box 14 is for "informational" purposes only, even tho it's important info for taxes paid to other jurisdiction for all employees living in Mass and working in RI. Is there anything else I can do to get a corrected W2?

No, there is no other way I can think of for getting the W-2C.  Follow the advice previously given and keep you documentation if you are ever questioned.

@user3466170

If I manually enter RI SDI in box 14 of the imported W2, will it affect IRS or State approval of the tax return when it's e-filed; could the return(s) be rejected because the info filed does not match the W2 as issued? 

If the return is efile rejected, then simply mail it in and remember to keep the backup for your records incase you do get a notice from the IRS claiming that whatever you reported doesn't match their records.