(Reuters) – Recruitment services firm Robert Half forecast first-quarter revenue slightly below Wall Street estimates on Tuesday, hit by sluggish hiring activity. Shares of the Menlo Park, California-based company fell more than 11% in after-market trading. Businesses are cutting back on recruitment services as they hire cautiously and lay off their employees to rein in costs in an uncertain economic environment. “While job opening demand continues to be above historical levels and candidate supply remains tight, the velocity of hiring remains impacted and there is less churn in the labor forc…