The following guidance was recently posted on the Texas Association of Realtors blog

Is it a violation of the Real Estate Settlement Procedures Act to indicate a title company in the MLS?
No, this alone would not be a RESPA violation. Similar to a price in an MLS listing, a title company in an MLS listing would be considered an offer to negotiate, not a required term of the contract. However, it would be a RESPA violation if the seller conditioned the sale of the property on the buyer purchasing the title insurance from the title company indicated in the MLS.