AIM-listed software firm K3 Business Tech has acquired Retail Systems Group (RSG) for £1.28m, a provider of Microsoft Dynamics 'Retail Management System' to retailers in the UK and Ireland.K3 said that this deal gives it access to the "significant market for smaller retailers." RSG has around 200 customers, including Aston Martin, Highgrove House and National Portrait Gallery.An additional £1.5m will be paid in respect of surplus cash in RSG, while an earn-out of up to £0.2m is payable over the next two years dependent on certain performance criteria."RSG represents another excellent acquisition for K3. We already have an established business delivering retail software solutions to mid-tier retailers and RSG will extend our reach into the substantial small retailer market," said K3 Chief Executive Andy Makeham.