I am an Indian citizen living in Singapore. I am publishing ebooks on Amazon, Apple, etc., and I have just gotten the EIN. I need help in Part II of the W-8BEN form, where it asks for the Article number and % rate. I saw the form and it doesn't mention Singapore at all.
First and foremost, I recommend that you talk to a tax professional who specializes in royalties if you're at all in doubt. I can give some information that might help, but I can't promise that it's completely accurate because I'm not familiar with international tax law as it applies to royalties.
That being said, the IRS instructions for the w8ben form (see p6) say that
Line 9a. Enter the country where you claim to be a resident for income tax treaty purposes. For treaty purposes, a person is a resident of a treaty country if the person is a resident of that country under the terms of the treaty.
Line 10 must be used only if you are claiming treaty benefits that require that you meet conditions not covered by the representations you make in lines 9a through 9e.
These lines are used if your country has a tax treaty with the United States that limits the tax rate on royalty income. According to the list of tax treaties, Singapore doesn't have such a treaty, so filling out lines 9a-9e in Part II may be sufficient.
This information doesn't apply to you because your country (Singapore) doesn't have a tax treaty with the United States, but I wanted to add it for future reference.
If you were a resident of a country that has a tax treaty with the United States, you would look up your country on the list of tax treaties and find the relevant treaty. For example, India has a treaty with the United States. In in Article 12, section 2A-2B (p16) of the treaty, it states that
Royalties and fees for included services arising in a Contracting State and paid to a resident of the other Contracting State may be taxed in that other State.
However, such royalties and fees for included services may also be taxed in the Contracting State in which they arise and according to the laws of that State; but if the beneficial owner of the royalties or fees for included services is a resident of the other Contracting State, the tax so charged shall not exceed:
(i) during the first five taxable years for which this Convention has effect,
(A) 15 percent of the gross amount of the royalties or fees for included services as defined in this Article, where the payer of the royalties or fees is the Government of that Contracting State, a political subdivision or a public sector company; and
(B) 20 percent of the gross amount of the royalties or fees for included services in all other cases; and
(ii) during the subsequent years, 15 percent of the gross amount of royalties or fees for included services;
Based on this information, an Indian resident would specify Article 12, and (I think) 15% because the tax treaty (referred to as the "convention" in the law) was passed in 1991, so more than five years have elapsed since it came into effect.
Disclaimer: My advice in the general case is the same as above: work with a tax professional who specializes in royalties to be absolutely sure this information is correct. I can't make any guarantee that the information provided here is correct, since I'm decidedly not a tax professional.