Numis Securities said it continues to see RPS's shares as "good value" despite the consultancy group disappointing the market with a trading update on Thursday.The broker maintained a 'buy' rating but cut its target price for the stock from 310p to 285p.RPS, which helps clients develop energy resources across the complete asset life cycle, said this side of the business has had a slower-than-expected start to the year."Management is anticipating an increased level of activity developing during 2015 once project costs plans have been defined. However the volatility in this sector means that the outlook is particularly uncertain," Numis said.The broker said it now expects a 15% decline in underlying energy revenues in 2015, compared with its previous -10% forecast.The company also announced the £22.3m purchase of Norwegian project management and training company Metier Holding, which will be integrated with RPS's own Norwegian project management unit OEC."The net impact of these two items [acquisition and trading update] on our EPS estimates is a c.5% downgrade. However, with an equity free cash flow yield of 10% we continue to see the stock as good value," the broker said.The stock was down 8.9% at 215.15p by 11:12.