Software: Intuit QuickBooks accounting software
The foreign vendor, which you imported goods from, is not a GST register trader; hence they will not indicate the GST on their bill.
However, when the goods arrived Singapore, you are required to pay the GST at the Custom (Sometime the forwarder may pay the GST on behalf of you).
Assuming the GST (7%) paid is $7,571.76 (that is based on an imported value of $108,168.00). You may use a Write Cheque transaction to record this payment.
The first line under the expense tab is $108,168.00 with 7% rated GST, and the second line will be a negative value of $108,168.00 without any GST associated. This is to contra off the value in the Cost of Goods Sold account.
The double entry for this transaction is:
Debit Cost of Goods Sold: 108,168.00
Credit Cost of Goods Sold: 108,168.00
Debit GST Payable: 7,571.76
Credit: Bank: 7,571.76
The Cost of Goods Sold account is a dummy account which you use to indicate the purchase value, you may consider to use a different account such as GST expense account.
This will also update the Tax report, under the Tax on Purchase section. $108,168.00 will be the taxable purchase and $7,571.76 is the input tax value.