By Verne Kopytoff

Diners who use OpenTable, the online restaurant reservation service, now can play the role of critic by writing reviews for the site.

The feature, available for Bay Area restaurants only, allows users to find out what others think about an establishment's food before booking a table.

OpenTable's foray into reviews places it in a crowded field that includes Yelp, a Web site where users share their views about everything from restaurants to park playgrounds. The move came after OpenTable, a 10-year-old San Francisco company, saw that 65 percent of its users read restaurant reviews by fellow amateurs on other Web sites, according to Scott Jampol, the company's senior marketing director.

Offering reviews is a delicate balancing act for OpenTable, which depends on restaurants for its livelihood by charging for every reservation it funnels them and for supplying a computer kiosk to manage the tables. Will those restaurants continue to pay OpenTable if negative reviews start to undermine their business?

Jampol said that the review system was developed to address what he called "restaurant angst." Some restaurants have an uneasy relationship with online review sites, which they accuse of allowing users to unfairly malign them.

Participation by the restaurants in OpenTable's review program is voluntary. Also, the submissions are policed in a way that makes them more reliable than other review sites, Jampol said.

E-mail review forms are sent only to people who made a reservation through OpenTable and were seated at the restaurant.

This is supposed to eliminate the problem of phony reviews - either from people who never ate at the restaurant or from disgruntled diners who submit several negative reviews about the same meal.

Reviews can also be removed for being too crass, off the topic or unhelpful. Reviews will be available only for 60 days.

Users can sort the reviews by date, rating and length. The site will have reviews suggested by the restaurant staff or chosen by OpenTable's moderators at the top of the page.

Restaurants are not able to respond to reviews on OpenTable. However, users, all of whom remain anonymous, can choose to receive a response privately by e-mail.

OpenTable's review feature started as a test with 750 Bay Area restaurants, while two restaurants chose not to participate, Jampol said.

There's no word on when or if it will be expanded to other metropolitan areas.