** Shares of Guangzhou R&F Properties 2777.HK climb 5.1% to HK$1.03

** Stock on track for the biggest one-day pct rise since April 9, if gains hold

** Chinese property developer says its total contracted sales for May amounted to 1.37 bln yuan ($190.68 mln) vs 970 mln yuan in May 2024; April 2025 contracted sales 1.36 bln yuan

** Hang Seng Mainland Properties Index .HSMPI gains 0.7%, while Hang Seng Index .HSI slips 0.2%

** YTD, stock down 27.9%

($1 = 7.1848 Chinese yuan renminbi)

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))