what is needed with the labeling of clothing using silk screen
In the United States of America, a registered identification number or RN # is a number issued by the Federal Trade Commission, upon request, to a business residing in the U.S. that is engaged in the manufacture, importing, distribution, or sale of textile, wool, or fur products. Such businesses are not required to have RNs. They may, however, use the RN in place of a name on the label or tag that is required to be affixed to these products.
Information in this RN data system is based on data submitted by private companies. The information is accurate and current only if it has been kept up-to-date by the registered company.
You can just use the number that is already on the blank shirt you use, or even leave the tag in there.