question for article expert

If the product and link are on your own site, yes. in the signature box.
If the product is an affiliate product, no.

That is the idea with article directories. But as artwebster said, don't directly link to affiliate product from article directories. Create a Landing page and link to that page.

Ok, thank you guys for the eye opener...

Actually guys, it depends on the directory. EZA won't let you, but others will.

You have to check each directory's submission guidelines.

AL

Everyone is right on with their comments above. Even though EZA doesn't allow affiliate links, I'm not sure I would go that route anyway. Even in articles directories that do allow such links, my personal opinion is that it is better to direct traffic to your own landing or pre-sell page first anyway. Here's one reason why.

Suppose a reader of your article clicks on a direct link to a vendor product page. They may have seen that page already and just went to your article for a review of the product. Why should they buy the product from you rather than some other affiliate? The answer is that almost all affiliates offer some kind of bonus when visitors buy through their links.

If, and this is a big if--but if you can create or obtain rights to a terrific bonus for people buying through your links--you can greatly increase your sales. Conversely, if you have a junk bonus--or no bonus at all--few if any people will buy from you.

The key is to get visitors to your pre-sell page, and don't try to sell them the product (the product vendor can do that better with their sales page than you), just raise their curiosity and hit them with a drop-dead bonus offer that no one else has. That will make you some money.