This form became obsolete in 2014. US citizens and Canadian citizens now automatically qualify for tax deferral similar to that available to participants in US retirement accounts such as IRAs and 401(k). You will qualify for this special treatment as long as you file and continue to file US returns for any year that you held an interest in an RRSP or RRIF and include any distributions on your US returns.
https://www.irs.gov/newsroom/irs-simplifies-procedures-for-favorable-tax-treatment-on-canadian-retir...
Please note that you will need to file one or two disclosure forms.
In fact, there are two separate disclosure forms that may be required; each also has different reporting rules. One is known as IRS Form 8938, which is included in TurboTax and can be attached to the relevant yearly Form 1040 tax return. The other is FinCen Form 114, which can only be filed via the internet. The following Internal Revenue Service webpage describes them in some detail, and provides their dollar value reporting levels:
https://www.irs.gov/businesses/comparison-of-form-8938-and-fbar-requirements
