The Loudoun County Board of Supervisors voted yesterday to place an $8 million bond referendum on the June 14 primary election ballot.

The bond authorization vote is to be divided into four parts - $5.3 million for two new elementary schools: $2 million for renovation of court facilities; $400,000 for park land acquisition and development; and $300,000 to expand the county sanitary landfill.

If an four bond issues pass, the county real estate tax will be increased by 2 cents per $100 of assessed value in 1977-78 and by 7 cents from 1978 until 1996, according to county estimates. The present real estate tax rate is 93 cents per $100 of assessed value with assessment based on 100 per cent of fair market value.

If the bond issues fail, the schools, one planned to open for the 1979 school year in Sugarland Run and the other in 1980 in Leesburg, will be built using general tax revenues. The court renovation also would be financed through general revenues, but the park and landfill programs would be dropped.

Financing the schools and court work out of general revenues would increase the real estate tax rate by 15 cents per $100 of assessed valuation in 1977-78; 31.1 cents in 1978-79 and 15.5 cents in 1979-80, according to county estimates.