KOO - I would assume you can buy in a TFSA as you are just buying RVX shares which are eligible. I would say that you would just include the $4.00 in you contribution room as that is all you are paying. You don't know at this time whether the warrants have any value ot not. They will not be trading and could be worth nothing or little with BoM failure. You really haven't paid anything for the warrants. If there is an issue, I would think it would come at the time you chose to exercise the warrants. That is when you are actually buying the extra shares and might have to include the purchase value at that time into your contribution room. I'm not saying this for sure, maybe just a possibility and maybe not since the warrants are already inside the TFSA but the extra shares aren't in the TFSA. That would take more investigation.  

Below is from a government site:

Warrants and options

1.38 In addition to listed warrants and options, certain unlisted rights are eligible for investment by registered plans. A warrant, option or similar right is a qualified investment for a registered plan if it gives the holder the immediate or future right to acquire property that is a qualified investment for the plan. The underlying property must be any of the following:

• a share, unit or debt of the issuer of the right (or of a person or partnership that does not deal at arm’s length with the issuer)
• a warrant issued by the issuer (or by a non-arm’s-length party) that gives the holder the right to acquire such a share, unit or debt